A lot of the things that consume us during a presidential campaign have absolutely nothing to do with what kind of a president any of the contenders will be. It isn't as though during the last three years we've said, "Boy, it sure was a good thing we spent all that time talking about Reverend Wright in 2008." But some things actually matter, and so it is with the discussion about whether Mitt Romney can comfortably appeal to voters in the center and to what degree he has to continue reassuring his conservative base. This will not cease to be a relevant question on the day he takes office. Instead, he'd be constantly confronted with choices that involve potentially angering conservatives. So it's useful to understand just what forces would be operating on a President Romney.
Steve Kornacki makes a useful comparison with George W. Bush, who despite his own rather profound conservatism found ways even as a candidate to distance himself from his party. And that was (for the most part) acceptable to his base:
For conservatives, the basic appeal of Bush was that he'd be their own Clinton – someone with similar charm and charisma who'd finally be able to deflect the Democratic attacks. They didn't want him straying too far ideologically, but they were more than happy to give him a lot of room to roam.
Today's conservatives aren't looking for another Clinton. They haven't faced a humbling defeat at Obama's hands (not yet, at least), and they believe adamantly that rigid adherence to their ideology is a winning national strategy. This doesn't mean Romney won’t try to distance himself, but if he does, he'll face a much fiercer backlash than Bush ever did.
One of the many differences between Bush and Romney is that conservatives trusted Bush. Even if he presented himself as "a different kind of Republican" (i.e. one who wasn't so cruel when it came to social issues), they knew that he was one of them. There was no doubt in their minds about where Bush stood on most things, and on most things he was with them. With Romney, they'll doubt everything.
We also need to understand this in terms of the day-to-day communication flows that end up in the Oval Office. Conservatives are going to be working very hard to keep Romney from departing from the ideological commitments he made to them; they won't just trust that he'll do the right thing. So they will be constantly lobbying the White House, offering a combination of threats and pleading. Every time President Romney goes to a meeting or a fundraiser, he'll be buttonholed by a conservative Republican who'll tell him that he darn sure better toe the line. That goes for the people around him too. The White House staff will be reminded on a daily basis that conservatives are restive and distrustful, in need of not just the reassurance that comes with attention (for instance, Karl Rove used to hold weekly conference calls with conservative Christian leaders when Bush was in office) but specific action. The counter-pressure from voters in the middle will come in more impersonal forms, like poll numbers.
That doesn't mean there won't be some occasions where Romney will face a choice between alienating the middle and angering the base, and the evidence will be overwhelming that the latter course is the one with the least political risk. But he can also count on conservatives to be much louder than they were during the Bush years, which could have a real impact on the decisions he makes.