And now, a two-candidate race: frontrunner Mitt Romney and barely-viable long-shot Rick Santorum.

There were really only two important questions in Iowa Tuesday night. Would Romney stay in the top three? Yes, he did. And: would Rick Perry, the only other candidate who has seemed like a plausible nominee, survive Iowa? No, he didn’t.

That’s it. As I write this, it’s still not clear in which order Romney and Santorum will wind up, with the networks just calling Ron Paul to finish a close third. But since I’ve been telling everyone for the last several days that it doesn’t really matter much which order the three of them finish in, I don’t see any reason to wait for my post-caucus wrap.

What matters is the spin over the next few days, and it doesn’t seem to me that the exact order of finish will affect that very much. Media biases — in favor of new things, unexpected things, and for keeping the race alive — should all help Rick Santorum become the big story coming out of Iowa as long as he finished at least third. But there’s another factor, too, and that’s what to watch for tomorrow and over the next few days: How do those Republican Party actors who don’t currently support a candidate choose to spin Iowa? Practically none will be talking up Paul. So will they push a pro-Romney or a pro-Santorum spin? That’s not going to depend on the finish in Iowa; it’s going to depend on their political preferences and interests. And the answer to that will probably determine whether Romney can wrap up the nomination by the end of January or whether we’ll have a tougher two-candidate race (with Paul hanging around) that could go on for a while. (See here for a much longer analysis of Santorum’s chances).

For the other three who competed in Iowa tonight, there’s no good news at all. The odds are good that Rick Perry and Michele Bachmann will drop out, as Iowa also-rans usually do. Newt Gingrich will probably stay in as an also-ran for a while, apparently alternating by the hour between loudly proclaiming his virtue in (frankly!) running a (fundamentally!) positive campaign and viciously attacking Romney. Since he won’t have the money to put those attacks in front of voters, it doesn’t matter much. Jon Huntsman has been campaigning hard in New Hampshire, which unfortunately for him isn’t a winning strategy. Expect Santorum to beat him there for third place, after which he’ll drop out. The big news, certainly, is that the once-viable Texas governor, the only candidate during the last six months who had a good chance to defeat Romney, is almost certainly done.

Which means what we have now is a two-candidate race for the nomination, with a solid leader in Mitt Romney and one remaining sort-of-viable long-shot, Rick Santorum.