There's been plenty of speculation about whether Mitt Romney's endorsement of John McCain in his primary battle with J.D. Hayworth will hurt Romney's prospects for the presidential nomination in 2012. Romney needs credibility with the party's dominant conservative wing -- something he lacked in 2008 -- and McCain is a bete noir to many in that wing. My sense is that Romney's endorsement of McCain won't be a problem unless McCain is re-elected and then softens his opposition to the Obama administration's liberal policies. I think it's quite likely that McCain will be re-elected, so the question becomes where he will stand thereafter. Will he be the hardliner we've seen since January 2009 or will the bipartisan McCain re-emerge? It's not easy to say. McCain's opposition to the policies of Obama-Reid-Pelosi are largely consistent with the principles he's espoused throughout his career. But it may also be driven to some degree by a combination (a) the prospect of having to seek re-election in 2010 and (b) hard feelings against Obama, like the ones he had towards President Bush that helped propel him to the left after 2000. It would be ironic if Romney takes a hit for supporting McCain. McCain was on his best behavior in 2007-08, and was typically charitable in discussing his rivals, such as Mike Huckabee and Barack Obama. But McCain was consistently contemptuous towards Romney, and attacked him mercilessly and, at times, dishonestly. Romney must have been tempted to seek revenge. But he's a measured guy and, I assume, he based his decision on forward-looking calculation. Time will tell whether he miscalculated.