The big question about the second debate of the presidential campaign—and perhaps the entire presidential campaign itself—is this: is this now a contest between Barack Obama and Mitt Romney or Mitt Romney and himself?

If it’s the former, Obama won tonight. Like Joe Biden before him, he spent more time on the offensive. He not only came out of the Libya discussion, potentially his most perilous, unscathed, but he flat-out won that portion of the night. He repeatedly and lucidly unloaded all the anti-Romney material that he didn’t mention in the first debate.

But it’s possible this race is no longer about Barack Obama. For days I’ve struggled to figure out why the first debate so dramatically shifted the polls. I don’t think it’s mostly because Obama was lousy. After all, most Americans have seen Obama speak well dozens of times; they know he just had an off night. The first debate moved the polls because Obama, through his passivity, allowed Romney to shine. Romney came across as competent, moderate, and normal—something he hadn’t managed all summer.

And I suspect—or should I say, fear—that the reason the polls moved so much is that there were a lot of voters who had tuned Obama out as a result of the bad economy. They were ready to vote against him so long as Romney passed a reasonable threshold, which he did. We’ve seen this before in presidential campaigns: in 1980, Americans were looking for an excuse to vote against the incumbent, Jimmy Carter, and so what mattered most in the debates was that Reagan didn’t look like a right-wing maniac. In 2008, Americans were looking for an excuse to vote against the de facto incumbent, John McCain, and so what mattered most in the debates was that Obama didn’t look like a novice. If the debates are really about people disillusioned with Obama becoming comfortable with Romney, it doesn’t really matter that Obama did better than Romney tonight because Romney did well enough. He again and again reminded Americans that the economy is worse than Obama said it would be, and he offered some kind of plan to make it better.

All year, the Obama campaign has been trying to make this campaign about Mitt Romney. It’s been an understandable strategy given the state of the economy, but it has also relied on Romney not being able to change the storyline about him that Obama began pounding home this summer. In the first debate, Romney did change that storyline, and tonight he did more of the same, appearing centrist, compassionate and hopeful.

If the Obama campaign can’t undermine the new, more likable image that Romney has created, it may not matter how well the president performs in the weeks to come. This campaign may now be Romney’s to lose.