“No matter how badly Iraq goes it helps the Republicans,” writes Tyler Cowen, “who benefit from an emphasis on foreign policy, an area where Democrats are never trusted.” This is a fairly widespread view. I give it additional credence because in my experience its main locus is among people who, like Cowen, have somewhat ambivalent feelings about the political parties. That said, I don’t see a ton of empirical evidence to back it up.
It’s obviously true that when the Democrats are conducting an unpopular foreign war (as in 1952 and 1968) this helps the GOP and that when the salience of a popular Republican policy sharply declines (as in 1992) this is good for the Democrats. But Jimmy Carter’s approval ratings were initially bolstered by, for example, the Iranian hostage crisis. It was only when, over time, the public came to disapprove of Carter’s handling of the crisis that the salience of this particular national security issue hurt Carter. Similarly, my understanding is that while Bush won the 2004 election, he non-trivially underperformed what had been predicted by deterministic models based on macroeconomic variables; one plausible explanation for this is that his popularity was being dragged down by Iraq.
The 2006 exit polls, I think, mostly support the view that concern with Iraq was an important source of Democratic strength. One should ask, I suppose, what Iraq is or is not crowding out in this scenario. When people are concerned about taxes, they tend to vote GOP. If they’re worried about health care, they’ll vote for the Democrats. I should note that there is reason to believe that fear and anxiety push people toward the Republicans.
Fundamentally, I’m open to counterintuitive arguments, but I refuse to believe that being responsible for a failing war automatically helps the Republican Party; I think a reasonably competent opposition party (not necessarily something that will emerge) ought to be able to turn Iraq to its advantage.