Patching it up

Nevertheless, in the voting booth, partisan loyalties may prove more powerful than racial prejudice. Benjamin Highton, a political science professor at UC Davis, studied 357 contested House races in the 1996 and 1998 elections. He found that white voters were no more or less likely to support black candidates than white ones. Prejudice against blacks still exists in many forms, but it does not guarantee that large numbers of Democratic voters will abandon an African American nominee for his white Republican opponent.

The reinforcement effect is especially likely to be strong this year, for two reasons. One is that partisan loyalties are increasingly salient to voters. Over the last 50 years, the proportion of Americans who identify with or lean toward either the Democratic Party or the Republican Party has held steady or slightly increased, according to the American National Election Study, the longest-running academic survey of political attitudes. Currently, 90% of the electorate identifies with one or the other major party. And during this same period, partisans have become increasingly loyal to their party's candidates, as in 2000 and 2004.

The second reason is that the Democratic and Republican parties have become more polarized, especially during the Bush administration. Democrats and Republicans are more divided in their views of President Bush and the Iraq war than they have been for any other president or war, according to data compiled by Gary Jacobson, a political science professor at UC San Diego. For instance, in a May Rasmussen poll, 70% of Republicans, but only 11% of Democrats, approved of the president. Given this gulf, most Democrats and Republicans are unlikely to find the opposing candidate attractive, especially after that candidate is criticized by their party's nominee for months on end.

The reinforcement effect, of course, doesn't guarantee victory for either party. In a close election, even a little party disloyalty can bring down a nominee. But history suggests that the discord we read about in the two parties today will fade, and Democrats and Republicans will coalesce around their candidates as Nov. 4 approaches.