Who is going to win in Michigan tonight? That’s a stumper: The polls show Mitt Romney and Rick Santorum dead even, with Nate Silver’s poll-based prediction model giving Romney a 55 percent chance of winning there. If I were pushed to guess, I’d go with Romney, figuring he’s going to have the better get-out-the-vote capacity . . . but that’s just a guess.

Who is going to win overall tonight? That’s easy: Unless the polls are completely wrong, Romney is going to have a good night. There are two states, not one, voting today, and Romney appears to have a solid lead in Arizona. Not only that, but Arizona, with 29 delegates at stake, is a winner-take-all state, while Michigan, with 30 delegates, has a more complicated allocation system, which will, if the overall vote is very close, almost certainly yield a split between Santorum and Romney. So Romney will almost certainly win more votes overall tonight, and unless Santorum does better than expected in Michigan (or pulls off a total shocker in the Grand Canyon State), Romney will increase his overall delegate lead.

One question, then, is how the press will cover the various plausible results. There’s a real opportunity for some mischief here. Remember, there’s a strong incentive for almost everyone – the press, the other GOP candidates, the Democrats – to emphasize all the uncertainties and to declare the nomination battle as wide open as they can get away with. The press wants people to keep watching. Santorum, Newt Gingrich and Ron Paul want to convince donors that they should kick in more money and volunteers that they aren’t wasting their time. The Democrats? They, of course, want as much chaos in the GOP as they can get. On top of that, there’s a natural tendency of the press to focus on the unknown (who will win Michigan) and ignore the apparently known (Arizona). There’s a real chance that everyone (but Romney!) will ignore Arizona and focus on Michigan, even though the delegate haul is similar and Romney’s victory there, should the polls be right, is actually quite impressive.

So far, the early returns are not promising. The New York Times’s home page right now leads with a Michigan story, and the Washington Post’s main politics page has numerous Michigan stories and not even a mention of Arizona. Some of that is reasonable, but too much emphasis of Michigan in coverage today risks really getting the story wrong. Remember, whatever happens with perceptions, there’s a delegate game going on, and the winner of that will be the Republican nominee. Reporting on today’s events should certainly make it clear that Mitt Romney has the delegate lead and is (presumably) lengthening it. That’s not the only story of today’s primaries, but it’s a big one, and it should not be overlooked.