Why Donors Give

A large body of work argues and empirically demonstrates that candidate ideology is relevant to individual donors' contribution decisions (Barber Reference Barber2016a; Barber Reference Barber2016b; Barber, Canes-Wrone, and Thrower Reference Barber, Canes-Wrone and Thrower2017; Bonica Reference Bonica2014; Brown, Powell, and Wilcox Reference Brown, Powell and Wilcox1995; Ensley Reference Ensley2009; Francia et al. Reference Francia2003; Gimpel, Lee, and Pearson-Merkowitz Reference Gimpel, Lee and Pearson-Merkowitz2008; Kujala Reference Kujala2020; Magleby, Goodliffe, and Olsen Reference Magleby, Goodliffe and Olsen2018), but it is challenging to identify precisely how ideology affects donors' willingness to give to candidates.

The extant literature is divided on how donors use candidate ideology when deciding who to support. Some argue that individuals contribute such de minimis amounts relative to the possible marginal political gains from influencing elections that donors must support candidates who share their views for the consumption value associated with expressing their views via an additional mode of political participation (Ansolabehere, de Figueiredo, and Snyder Reference Ansolabehere, de Figueiredo and Snyder2003).Footnote ³ If donors primarily give to express support for like-minded candidates, the distribution of donations across candidates will reflect donors' ideologies rather than the importance of strategic considerations such as the competitiveness of the election.Footnote ⁴ This behavioural model of ideologically expressive giving is the basis of donation-based measurement models of contributor and recipient ideology (for example, CF scores [Bonica Reference Bonica2014] and those developed by Hall and Snyder [Reference Hall2015]).

Others claim that while donors are most likely to contribute to ideologically aligned candidates, they also give to misaligned candidates with decreasing probability as the ideological distance between them grows (Barber Reference Barber2016b; Barber, Canes-Wrone, and Thrower Reference Barber, Canes-Wrone and Thrower2017; Kujala Reference Kujala2020). Donors are commonly assumed to be indifferent between candidates who diverge in either direction, but they may also care about the direction of the divergence. On the one hand, donors may allocate greater resources to candidates more moderate than themselves if moderates are expected to be more electorally successful than extremists (Hall Reference Hall2015; but see Utych Reference Utych2020). Conversely, the greater electoral vulnerability of extremists, all else equal, may lead donors to believe that they are in greater need of financial support than moderates. Donors who give with an eye toward the subsequent lawmaking environment may also prefer to support more extreme candidates who are less likely to compromise with the opposition party (Groseclose and McCarty Reference Groseclose and McCarty2001; Lee Reference Lee2016) and most likely to move the legislative party median closer to donors' extreme preferences (Barber Reference Barber2016c; Cameron and Kastellec Reference Cameron and Kastellec2016; Krehbiel Reference Krehbiel2007; Patty and Penn Reference Patty and Penn2019).

Understanding the importance of candidate ideology relative to other considerations is important for contextualizing the potential effects of donations on the larger political system. Given donors' extreme preferences, those who give solely on the basis of ideological alignment may contribute to elite polarization (Barber Reference Barber2016b; Kujala Reference Kujala2020; La Raja and Schaffner Reference La Raja and Schaffner2015). However, if donors prioritize strategic factors, such as whether a candidate is running in a competitive district due to the importance of majority control for passing legislation (Cox and McCubbins Reference Cox and McCubbins1993), the incentives for candidate extremism may be more muted. Indeed, prior work has found that donors report caring about affecting electoral outcomes (Barber Reference Barber2016a) and are more likely to contribute to Senate candidates in competitive races (Barber, Canes-Wrone, and Thrower Reference Barber, Canes-Wrone and Thrower2017) and give to close races out-of-state (Gimpel, Lee, and Pearson-Merkowitz Reference Gimpel, Lee and Pearson-Merkowitz2008). Issues of endogeneity have made it difficult to assess how important district competitiveness is to donors' decisions compared to the ideology of candidates,Footnote ⁵ and it is also unclear whether donors prefer giving to candidates running in districts that lean toward or against their party.Footnote ⁶

Donors may also respond to the characteristics of a candidate's opponent (Barber Reference Barber2016a; Magleby, Goodliffe, and Olsen Reference Magleby, Goodliffe and Olsen2018). For example, those facing an incumbent opponent may be less likely to receive contributions because incumbents are historically more difficult to defeat (Abramowitz, Alexander, and Gunning Reference Abramowitz, Alexander and Gunning2006; Thomsen Reference Thomsen2023; but see Jacobson Reference Jacobson2015). At the same time, donors may prefer giving to candidates challenging incumbents because defeating an incumbent of the opposing party shifts the overall chamber margin by two seats. An ideologically extreme opponent may also increase donors' willingness to contribute, similar to how voters turn out in greater numbers for candidates running against extreme opponents (Hall and Thompson Reference Hall and Thompson2018). This would be consistent with a concern that the election of an extreme opponent will push the opposing party's policy even further away from the donor than the election of a more typical opponent (Hill and Huber Reference Hill and Huber2017).

A final set of potential considerations for donors emerge from the large literature on ‘quality challengers’. Donors may rely on characteristics related to prior legislative experience, fundraising, and interest group support to identify candidates who are more likely to be electorally successful (Biersack, Herrnson, and Wilcox Reference Biersack, Herrnson and Wilcox1993; Box-Steffensmeier Reference Box-Steffensmeier1996; Jacobson Reference Jacobson1989; Maestas and Rugeley Reference Maestas and Rugeley2008). If donors contribute strategically to help their party win or retain seats, they may prefer to support candidates who are thought to be viable based on district enthusiasm, endorsements, strong fundraising, or favourable previous electoral performance. Although such traits have been associated with winning in the past, so-called ‘newcomers’ may also be increasingly seen as viable given contemporary patterns of candidate recruitment (Bawn et al. Reference Bawn2012; Porter and Steelman Reference Porter and Steelman2023).

One complication is that the importance of these considerations may vary across donors. Donors differ in many ways, but a question of particular interest in understanding their potential impact on political polarization is whether those who are the most extreme behave differently than those who are more moderate. Even if all donors prefer giving to extreme candidates over moderate candidates to help pull their party caucus closer to the donors' comparatively extreme preferences, extreme donors have the most to gain (and lose) from changes in majority control because of their relative extremity (Barber Reference Barber2016c). Consequently, it is unclear whether they support more extreme candidates to try and shift the ideological makeup of the party caucus or more moderate candidates better aligned with rank-and-file voters, presumably making them more electable (and majority status more likely).

Research on polarization at the mass and elite levels, which shows greater polarization among Republicans than Democrats (Hacker and Pierson Reference Hacker, Pierson and Persily2015; Mann and Ornstein Reference Mann and Ornstein2016; Theriault Reference Theriault2006), also suggests that the importance of these considerations may vary by partisanship. While it is impossible to know whether differences reflect variation in partisans' priorities – for instance, recent work argues that the parties differ in the relative importance of ‘issues’ versus ‘identity’ considerations (Grossmann and Hopkins Reference Grossmann and Hopkins2016) – or their political context – donors in 2018 were giving to candidates following the 2016 election, where the Republicans took control of both the presidency and Congress – arguments about asymmetric polarization make it important to determine whether Democratic and Republican donors respond similarly to candidate and electoral characteristics.

In addition to the fact that donors of different ideologies and parties may weigh considerations differently when deciding whether to support a candidate, it is also plausible that these motivating considerations interact with one another. Estimating the average effect of a factor while holding all else equal may obscure the conditional nature of the relationship between different considerations, especially among strategic donors. In particular, donors' willingness to give to candidates who are more extreme or more moderate than themselves may depend on whether the candidate is running in a more or less safe district (Baron Reference Baron1994) or against an extreme opponent (Woon Reference Woon2018). Understanding whether the impact of certain factors depends on others is important for evaluating both the extent of donors' impact on the political environment and the types of research designs that can be supported in the presence of such selection effects.

Research Design and Experimental Vignettes

Research on individual donors' contribution decisions largely relies on either aggregate-level donation patterns (for example, Barber Reference Barber2016b; McCarty, Poole, and Rosenthal Reference McCarty, Poole and Rosenthal2006; Stone and Simas Reference Stone and Simas2010) or self-reported motivations from surveys (for example, Canes-Wrone and Gibson Reference Canes-Wrone and Gibson2019; Rhodes, Schaffner, and La Raja Reference Rhodes, Schaffner and La Raja2018). Such studies provide important insights, but both approaches are limited in their ability to isolate the relative effects of multiple factors on donors' decisions. We seek to complement existing findings by providing more specific interpretations of their general patterns and by identifying new patterns in donor behaviour that are difficult or impossible to capture using extant approaches.

Consider, for example, the meaning of the above-average level of funding we observe in competitive districts. Does this reflect ideology-driven donors giving to like-minded candidates who happen to run in competitive races? Or are donors giving to help their party win close races, regardless of the candidates' positions? Alternatively, perhaps donors are choosing to support high-quality candidates who are more likely to be recruited to run in pivotal races. It is even possible that donors know nothing about the candidate they are supporting, given contemporary fundraising practices that encourage contributions to races about which an individual may know little. Making strong inferences about motivations using observed donation patterns is – to put it lightly – challenging due to inevitable problems of confounding, omitted variables and endogeneity caused by the strategic behaviour of candidates, donors, and parties.

Given the difficulties with observational data, some have chosen to directly question donors about their motivations for contributing (for example, Barber Reference Barber2016a; Barber, Canes-Wrone, and Thrower Reference Barber, Canes-Wrone and Thrower2017; Francia et al. Reference Francia2003). In a survey of 2012 Senate donors, Barber (Reference Barber2016a), for example, finds that ideologically extreme donors were more likely to report that a candidate's ideology, the opponent's ideology, and a chance to shape the election outcome were all important reasons for giving. While this work clearly demonstrates that donors consider multiple factors when giving (Magleby, Goodliffe, and Olsen Reference Magleby, Goodliffe and Olsen2018), the relative importance of each factor and how donors trade-off between competing considerations is unclear. Moreover, it can be difficult to interpret what it means for a consideration to matter in donation decisions. If donors report valuing a candidate's ideology, for example, it could mean that they (1) only contribute to like-minded candidates, (2) are willing to give to candidates with whom they disagree, but less so as candidates grow ideologically distant, or (3) have a general preference for supporting more extreme candidates over more moderate candidates, or vice versa.

To both examine the relative importance of candidate, opponent, and district characteristics in donors' willingness to contribute and to avoid ambiguity associated with interpreting survey responses, we combine the advantages of interviewing verified donors with the causal identification provided by the randomization of candidate and electoral characteristics in a multifactorial experimental vignette. We randomly selected nearly 69,000 verified donors from the 2018 midterm elections using Targetsmart's national database of itemized donors, including all congressional donors who gave over $200, as well as those who contributed to campaigns that voluntarily disclosed smaller donations.Footnote ⁷ Each selected donor was sent a letter, and half were also sent a follow-up reminder postcard inviting them to participate in an online survey in return for a $1 charitable contribution made on their behalf. Ultimately, 7,335 verified donors completed the survey (10.6 per cent), which included vignettes gauging respondents' likelihood of contributing to a hypothetical same-party candidate whose ideology, viability, electoral context, and opponent characteristics were experimentally manipulated.

Table 1 presents the weighted and unweighted demographics of our donor sample. As expected, given prior studies of donor demographics, donors tend to be older, highly educated, very wealthy, and the majority are male (Hill and Huber Reference Hill and Huber2017). To ensure that our respondents are representative of our sampling frame, we construct individual respondent weights to match the distribution of respondent demographics to the demographics of the sampling frame (which was itself a random sample of the population of midterm donors).Footnote ⁸ Democratic donors are overrepresented in the sampling frame because more Democrats contributed during the 2018 midterm election than Republicans and, consistent with larger non-response patterns in polling (Clinton Reference Clinton2020), Democrats were more likely to respond to the survey than Republicans.Footnote ⁹ To account for partisan differences, we also conducted separate analyses for Democrats and Republicans in Appendix D.

Table 1. Donor self-reported demographics

The table includes all respondents who finished the survey and self-identified with a party. The weighted sample is smaller due to missing survey weights based on voter file information. Appendix G reports the raw sample demographics in terms of voter file demographics.

In addition to directly asking about motivations for giving (see Appendix A), our primary analysis examines donors' likelihood of contributing to hypothetical same-party candidates that are described with particular sets of randomized traits, opponents, and electoral environments. Our experimental vignette approach has three key advantages. First, the independent randomization of candidate and election characteristics in each vignette allows us to isolate their effects without dealing with the issues of omitted variable bias, collinearity, and endogeneity that are present in analyses of observed donations. Second, because we present each donor with several randomized multifaceted vignettes, we can directly characterize the relative importance of every factor for different donors. This also allows us to estimate the effects of one consideration conditional on randomized changes in another. In so doing, we are careful to minimize potential concerns about design-induced demand effects by providing donors with an entirely new randomized combination of characteristics each time they evaluate a hypothetical candidate. Third, to avoid the difficulties associated with trying to locate candidates and donors on a comparable and commonly understood ideological scale, we explicitly define candidates' ideology relative to the donor's own ideology.

Of course, no research design is perfect, and relying on an experimental vignette introduces a few limitations. First, we must measure self-reported intent to give rather than actual giving. Even if this leads respondents to overestimate their actual likelihood of giving, it will likely bias the relative effects of each consideration rather than the intercept. Second, because we present respondents with multiple vignettes composed of randomized descriptions, the vignettes are necessarily generic and abstract. On the one hand, this is desirable because it avoids problems associated with omitted variables arising from information respondents have about real candidates, as well as bias that might originate if respondents felt external pressure to report supporting specific candidates. On the other hand, hypothetical candidates lack other features that may affect donations, such as public reputation, professional ties, or campaign style – considerations that are more likely salient when donating to in-state candidates. Together with the vignette description of hypothetical candidates as running in a state other than the respondent's, the design generalizes better to out-of-state giving than to in-state giving.Footnote ¹⁰

All randomized vignette features are described in Table 2. We introduced the vignettes as follows: with text in << >> indicating randomly assigned features and text in [[ ]] indicating features based on prior survey responses:

Table 2. Randomized vignette features

Each respondent was randomly assigned either five primary or five general election vignettes. All features were randomly assigned with equal probability in each vignette.

Although respondents are instructed to imagine being solicited by the candidate, the candidates are presented using neutral descriptions rather than in the language candidates would typically use in their own appeals, making the design more akin to donors choosing to give of their own initiative rather than reacting to fundraising solicitations.Footnote ¹¹ While donors who did not identify with either of the two major political parties were randomly assigned OWN PARTY as either ‘Democratic’ or ‘Republican’, we focus on the 94 per cent of donors who identified as one or the other. For each donor, all five vignettes were randomly assigned <<RACE TYPE>> of either ‘Primary’ or ‘General’ in order to ease the cognitive load and minimize confusion. Asking about both general and primary elections allows us to determine whether donors' calculations differ when deciding to contribute to candidates in intra-party versus inter-party contests. Each vignette had the following structure:

The outcome of interest is the donor's reported likelihood of contributing to the hypothetical candidate on a five-point labelled scale: I would almost certainly NOT contribute (0–10 per cent), Not very likely (10–35 per cent), Close to even (35–65 per cent), Very likely (65–90 per cent), and I would almost certainly contribute (90–100 per cent). For ease of interpretation, we present results with a binary outcome of whether the donor was very likely or almost certain to contribute (1) or not (0), with parallel specifications using the linear scale reported in Appendix E.

To investigate the effect of candidate ideology on giving, we randomly assign the hypothetical same-party candidate to either share the donor's views on policy, hold views that are somewhat more extreme, hold views that are much more extreme, or hold views that are somewhat more moderate than the donor's.Footnote ¹² Recognizing that Democratic and Republican respondents react differently to candidates described as more liberal or conservative than themselves, we also vary the description of the candidate's ideology depending on the donor's partisanship, as outlined in Table 2. For example, for Republican donors, we describe the candidate's policy positions as either ‘about the same as yours’, ‘somewhat more conservative than yours’, ‘much more conservative than yours’, or ‘somewhat more liberal than yours’, with the last option corresponding to being more moderate than the donor. In addition to explicitly describing the candidate's ideology in reference to the donor's, using the terms ‘liberal’ and ‘conservative’ rather than ‘extreme’ and ‘moderate’ helps minimize confusion for donors who consider themselves moderate or ideologically misaligned with their party.Footnote ¹³

Figure 1 presents the basic relationship between candidate ideology and donors' willingness to give. Consistent with prior findings, the largest percentage of donors (39 per cent) report wanting to contribute when the candidate is described as holding policy views that are ‘about the same’ as their own. More novel, however, is the fact that the willingness to give decreases only slightly (to 36 per cent) for candidates with somewhat more extreme views than the donor's and slightly more (to 30 per cent) for much more extreme candidates, while the largest decline is present for candidates described as somewhat more moderate than the donor (only 21 per cent). Far fewer donors report being willing to support a candidate who is more moderate than themselves relative to a candidate who is more extreme, providing preliminary evidence of donors penalizing moderation more than extremism.

Figure 1. The proportion of donors wanting to give by candidate ideology. The horizontal axis is randomized candidate ideology, described relative to the donor's own positions. The vertical axis is the percentage of donors who indicated being very likely or almost certain to contribute to the candidate.

As Table 2 details, we also randomize other features of the race. This allows us to evaluate the average impact of candidate ideology on donors' decisions relative to the impact of other considerations, as well as whether donors respond differently to candidates' ideologies depending on these other race features. The partisan ‘lean’ of the district in which the candidate is running is said to lean toward the respondent's party, the opposition party, or be a pure toss-up.Footnote ¹⁴ We also vary the extremity and incumbency status of the candidate's opponent. Finally, the same-party candidate is described as either a political newcomer, having received key endorsements, raising a good deal of money, and having barely lost a prior election, or running in a district that is enthusiastic about the candidate.

To allow for non-linear treatment effects, we estimate the relationship using indicator variables for every value of the randomized traits. For expositional ease, we focus on an additively separable specification that models the likelihood of donor i contributing to the candidate described in vignette v using:

$$\eqalign{Pr( Y_{iv} = 1) & = \alpha + \beta _1\;{\rm Candidate}\;{\rm Ideolog}{\rm y}_{iv} + \beta _2\;{\rm District}\;{\rm Lea}{\rm n}_{iv} \cr & \quad + \beta _3\;O{\rm pponent}\;{\rm Extrem}{\rm e}_{iv} + \beta _4\;{\rm Opponent}\;{\rm Incumben}{\rm t}_{iv} \cr & \quad + \beta _5\;{\rm Candidate}\;{\rm Viabilit}{\rm y}_{iv} + \gamma {\rm Primary}\;{\rm Rac}{\rm e}_i + \delta _v + {\rm \epsilon }_i.} $$

where Y _iv = 1 denotes whether respondent i reported that they were either very likely or certain to contribute to the candidate as described in vignette v. In accordance with Table 2, Candidate Ideology represents separate indicators for whether the candidate is described as being somewhat more moderate, somewhat more extreme, much more extreme, or has about the same ideology (base condition) as respondent i, allowing for non-linear effects. For District Lean, the district either leans toward the respondent's party, leans toward the other party, or is a toss-up (base condition). Opponent Extreme indicates whether the opponent is extreme rather than typical (base condition) and Opponent Incumbent designates whether they are an incumbent rather than a new candidate (base condition). Candidate Viability is a set of indicators for whether the candidate has either received key endorsements, raised money, believes that the district is enthusiastic about the candidate, barely lost last time, or is a newcomer (base condition). We include vignette order fixed effects (δ _v)Footnote ¹⁵ and cluster standard errors at the respondent level.Footnote ¹⁶

The specification also includes an indicator for whether respondent i was assigned primary or general election vignettes to allow for differences in the willingness to contribute by election type (γ). Although campaigns may believe donors' motivations differ in the primary versus general elections (Hassell Reference Hassell2011), Appendix D reveals similar average estimated conditional effects for primary and general election vignettes.Footnote ¹⁷ Donors were less likely to report a willingness to contribute to candidates running in primary elections overall, but the estimated incremental effects of the randomized considerations on donors' willingness to give did not vary across election types. Consequently, we pool analyses across primary and general election vignettes.

Although we focus on an additively separable specification, there is reason to think that the effects of various factors are interdependent. Existing research suggests that donors' response to candidate ideology may have an interactive effect on district competitiveness (Baron Reference Baron1994) or the presence of an extreme opponent (Woon Reference Woon2018). To account for strategic interactions, we investigate differences in the effects of candidate ideology by district and opponent treatments in Appendix D. Regardless of whether the candidate was described as running in more-or-less competitive districts or facing an extreme opponent, donors reacted similarly to the same-party candidate's relative ideology.