A big night for Mitt Romney indeed, as he wins in Arizona and Michigan. Tonight was the Republican nomination battle in a nutshell. Lots of excitement, and if you spin it the right way you can find lots of weaknesses for Mitt Romney…but at the end of the night, you remember that Romney basically has had the nomination nailed down for a while now.

He didn’t need Michigan – he would have had a good night even if he lost by a few points there, since he would have gained in the delegate count – but it helps make it more clear than ever that he’s going to be the nominee. The short-term question now is whether he can get a reasonable bounce out of it and into Super Tuesday next week, on March 6. As I’ve said after each round, that depends more on the spin war than on the actual election returns. What’s working for Romney: He has an overwhelming lead among Republican opinion leaders, who may want to try to shut this thing down for good. What’s working against him: Everyone who has an interest in keeping it going as long as possible, which certainly includes the press. Perhaps the deciding vote goes to those conservative opinion leaders, including quite a few elected senators and governors, who have sat on the sidelines so far. A sudden surge in support for Romney might well start a bit of a stampede to him that voters would jump on.

The truth is that it doesn’t matter all that much at this point. Mostly, what’s at stake is whether the general election campaign starts a few weeks earlier or later. Republicans are nominating someone who will function, basically, as a generic Republican; Romney’s no master politician, but he doesn’t have any of the significant weaknesses of a Rick Santorum, not to mention the massive weaknesses of Newt Gingrich. And yet they’re going to nominate him only after pushing him on issue after issue to adopt a Tea Party platform. That’s good for conservatives if he wins, but on balance it will tend to make a November victory a bit harder for him. At any rate, enjoy these last few weeks of primary elections while they last, because we’re about to have a very, very long general election campaign.