War casualties in Iraq may play an important role in the presidential election this fall, suggests new research by UC Davis political science professor Scott Sigmund Gartner.

A study conducted by Gartner and Gary Segura, a political science professor at Stanford, reveals that members of Congress whose districts faced a disproportionate number of casualties in the weeks before the 2006 midterm elections were punished at the polls.

The research suggests that an increase in casualties prior to the election will hurt Republican presidential candidate John McCain because the Arizona senator has refused to withdraw troops until the Iraq government has been stabilized. However, the effect of these casualties may not by themselves be enough to tip the election in favor of Democratic opponent Sen. Barack Obama -- who has called for immediate withdrawal to prevent any further casualties -- because there are other factors that may help McCain and hurt Obama, Gartner said.

The study, titled "All Politics are Still Local: the Iraq War and the 2006 Midterm Elections" and published in the April issue of PS: Political Science, the journal of the American Political Science Association, analyzes how recent and cumulative casualties from the Iraq War affect voters at the state level. Voters use casualties to measure the war's cost. Along with other factors, such as ongoing revelations of pre-war intelligence failures and manipulations, this human cost then impacts how voters choose their candidates.

"Local military casualties create a local political lens through which people view these national issues," Gartner said. "These recent casualties are more salient to voters because it leads to more news coverage, thus bringing the trauma closer to home as individuals can now translate an abstract number into a loss that is more personal and meaningful."

Consequently, the states that experienced the most casualties from the Iraq war often replaced their incumbents with Democrats, even among those states that had previously voted Republican. For example, among states holding senate elections, Montana, Rhode Island, Pennsylvania, Virginia, and Missouri were among the top 12 states in numbers of recent per-capita casualties, and their respective incumbent Republican senators received only 48, 47, 41, 49, and 47 percent of the vote share.

Incumbents are usually held responsible for a war's costs, according to Gartner and Segura.

"War has local political effects. It creates an American experience, a state experience, and even a town-by-town experience, and this influences the public's perception of leaders and conflict," Gartner concludes.

In a related study published in February in the American Political Science Review, Gartner proposes a political science theory that he calls the "rational expectations theory of casualties and opinion." The theory is based on the observation that public support for elected leaders diminishes as both recent casualties and casualty trends increase. In particular, he argues that people use trends to interpret recent casualties. Thus, for example, how people react to a high-casualty month depends on whether casualties were high or low during previous months.