Now that Rick Santorum has suspended his presidential campaign, we are going to see the inevitable slew of articles on how important/challenging it will be for Romney to win over Santorum’s voters for the general election (see here and here for example).
From the perspective of someone who studies comparative politics (otherwise known as domestic politics outside the United States), I would strongly urge the Obama campaign not to hold its breath over the possibility that the Santorum voters will somehow stay away from Romney in the fall. While of course it is possible that some Republicans who dislike Romney might be less likely to campaign for Romney or donate money to him than if Santorum had gotten the nomination, Romney is greatly helped by the fact that the US employs a presidential system of government. In the parlance of political science, the US presidency is a zero-sum contest: you either win or lose. As such, as long as Republicans can unite around a desire to unseat the president (which most will), the structure of the election provides no other viable option than to vote for Romney in order to accomplish that goal.
Moreover, the world is full of examples of political forces coming together under a common banner that have much less in common than the conservative and moderate wings of the Republican party to accomplish the shared goal of getting rid of a particular leader. One need look no farther than recent anti-Putin protests in Russia, which have featured collaboration between far-right nationalists, far-left communists, and liberal democrats. Indeed, part of the story of the collapse of communism in East-Central Europe was one where “umbrella movements” came together to oppose communist rule, only to break up into distinctly different parties once communism had collapsed. While I’m not suggesting that the Republican party will collapse following a Romney victory, the point is that whenever you have a zero-sum game, it is not surprising to find even forces with very different long-term interests putting aside those differences to collaborate on short-term goals.
I would even go so far as to say it is safe to ignore poll data taking during the campaign that might have suggested Santorum voters would rather stay home than vote for Romney. As I argued at approximately this time four years ago, there are rational reasons for supporters of a candidate to tell this to a pollster during a primary campaign (as well as psychological ones I’m sure), but it does not mean that voter won’t return to the fold come the general election.
One caveat is in order: I am not advancing the claim that the Republican primary has not hurt Romney. It may very well have damaged his standing among independents and/or provided valuable fodder for the Obama campaign down the road. But I seriously doubt that pushing Santorum supporters away from voting for the Republican ticket in the fall will turn out to be one of those consequences.