Does the EU’s performance compared to neighboring countries influence public support? Using a benchmarking approach, we argue that people compare their country’s performance within the EU to that of a non-EU country, shaping their attitudes. The COVID-19 vaccine rollout in 2020 provides an ideal test case, as governments launched vaccination programs at different speeds. The UK began weeks before EU countries, allowing us to examine its impact on EU support. Using an Unexpected Event during Surveys Design (UESD) with Eurobarometer data, we find that the UK’s early rollout significantly reduced specific policy support for the EU but did not consistently affect diffuse support. Our findings offer key insights into attitudes toward European integration and performance evaluations.