Published online by Cambridge University Press: 28 June 2011
In the 2008 presidential nomination campaigns, both Obama and McCain staked out clear positions on the Iraq war. Exit polls conducted in primary and caucus contests show that the war in Iraq was indeed the key issue of support for the winning contenders. However, it was not agreement with the candidates' positions that drove primary voters into the arms of Obama and McCain; rather, it was concern with the Iraq war. Primary voters treated the war as a valence issue, not as a position issue. Each candidate also won an early contest (the Iowa caucuses for Obama and the New Hampshire primary for McCain) in which concern over the Iraq war was especially strong. Those victories sparked a momentum for both candidates in subsequent contests. As a result, both Obama and McCain owed their respective nominations for president to the combination of war and momentum.