Mitt Romney had to thread a very small needle during Monday's foreign policy debate. He had to hew closely to President Obama's foreign policy while somehow seeming stronger than Obama. He had to seem ready to attack our enemies in order to keep his fellow Republicans interested, while still seeming like enough of a pacifist to calm Americans who don't want to get involved in another endless war. And he had to somehow transform his own total lack of foreign-policy experience—his entire ticket's lack of foreign-policy experience, in fact; this is the most inexperienced pair of Republican candidates in modern history—into an asset.

He failed on every single count.

Romney looked inexperienced, sweaty, discombobulated, and even scared all night long. At times, he sounded like a pacifist. At other times, he presented himself as a George W. Bush–like warrior, skipping from conflict to conflict with the phony swagger that only money and a hearty sense of inflated self-importance can buy. Neither act was convincing.

This final debate was, in many ways, the reverse of the first debate. Obama was calm, in command, and strong. Romney was absent and ill-prepared. There were shades of the vice presidential debate, too: Obama, like Joe Biden, resorted to outright mockery of his opponent's lack of preparation. His sarcastic riff on Romney's lack of understanding about the modern military ("we have these things called aircraft carriers where planes land on them") was brutal, but it drove the point home: Obama knows what he's talking about when it comes to military matters. And he intellectually bested Romney again and again, often with touching, personal stories of the sort that Bill Clinton used to share all the time.

And best of all, Romney's "safe" strategy reminded Republicans that he isn't a champion of their precious, pure conservative thought. Romney will say anything to be president, and if that involves becoming an Obama clone to try to strip moderate votes, he'll happily do that. I suspect that some of that vaunted Republican enthusiasm for Romney will drain, now that their candidate revealed himself so blatantly as a changeling. Republicans could now be entering a smaller-scale version of the tailspin that Democrats experienced after the first debate. With two weeks to go, that could make a huge difference on Election Day.

Don't expect the polls to tip one way or the other in huge numbers—not at this late date. But Monday was a palpable win, an even clearer win than the second presidential debate. That's not nothing. This is probably the best possible ending to the debate cycle that the Obama team could have hoped for. The rest is up to them, and all of us.