For all of his gaffes and unforced errors, it's important to remember that Mitt Romney never promised to be a likeable presidential candidate, or someone for whom personality was a selling point. The point of Romney has always been that he is a generic Republican candidate, with the skills and profile necessary to win a general election. He has conventional experience (a business career with a stint in the public sector), a conventional persona (competent businessman), and a standard-issue message-the economy is off-track, and only I can bring it back to station.
The simple fact is that this is more than enough to win the general election. Even the most optimistic predictions have unemployment clocking in at 8 percent by November, and while the rate of change is more important than the overall number, the economy won't grow fast enough for Barack Obama to cruise to reelection. By definition, a major-party presidential nominee has a good chance of winning the presidency, and the fundamentals of this election increase the odds for Romney, who has everything he needs to secure a win.
All of this is to say that Romney's main obstacle isn't himself. Left to his own devices, there is no doubt that the former Massachusetts governor would be a confident, competent challenger to President Obama. Indeed, throughout the campaign, he has done his best to ignore his competitors and present himself as the general election nominee. But Romney's dilemma is that the GOP won't let him be a generic Republican nominee. From the perspective of a conservative voter or activist, this makes sense. The problem with generic Republican nominees is that they tend to run to the center, and attempt to minimize the extent to which they are conservative. In the last election, we lost big time with a moderate, so let's try the opposite approach and run away from the middle. If we lose, we lose with dignity, and if we win, we'll have an outspoken conservative in the White House. As party participants with a strong interest in conservative policy, they want to maximize the ideological gains of a win.
The problem is that, by virtue of his genericness, Romney is ill-suited for the task. Because of his attempt to get ahead of his conservative opponents, the primaries have minimized some of the distance between Romney and the Republican base. Still, they don't trust that he'll follow their lead in the general election if he wins the nomination.
To avoid a repeat of 2008, they will force him into the role of conservative standard-bearer, and this-more than anything inherent to his campaign-is what will hurt him in the general. He'll have to champion right-wing ideas, defend unpopular conservative policies, and promise to govern as a movement conservative (more so than he already has). It will be the same dynamic as the primaries-on a much larger stage-and because the Republican Party remains unpopular, it will do nothing but hurt his standing with the public.
To be captive to your base is the worst possible situation for a presidential candidate in a closely-divided electorate. Unfortunately for Romney, there's not much he can do about it.