There are two contests today, in Arizona and Michigan, but only Michigan is really up for grabs. That’s because Mitt Romney can count on a large and active Mormon population in Arizona and the support of almost all the Arizona GOP establishment (though that endorsement from Gov. Jan Brewer might cut both ways). Plus Rick Santorum put most of his energy into Michigan, Romney’s home state.

Though Romney’s camp has been playing down the importance of Michigan — the truth is that, unless there’s a blow-out, the delegates will be split pretty evenly no matter who wins — there’s still plenty at stake in our Great Lakes neighbor.

Here are five things to look for in today’s primaries:

1. The margin

No matter who wins, what will matter is the margin. If Romney squeaks by, Santorum will rightfully call it a moral victory. And a squeaker-win for Romney will do nothing to hurt Santorum’s momentum or fundraising. If Santorum wins, he’ll get plenty of help from the western part of the state, but if he has substantial margins in the east — Detroit, etc. — then his argument for electability will get a huge boost. (For that matter, Romney’s gotta win by double-digits in Arizona to make all that effort worthwhile.)

2. Abandon ship!

If Santorum wins Michigan, it doesn’t necessarily mean the death knell for Romney. But it will mean that the Republican base is so alienated that he’s practically guaranteed a loss if he’s the party’s standard bearer. If Romney loses here, watch the GOP turn into an Every-Man-For-Himself party and watch the endorsements dry up fast for Romney in every upcoming primary. Nobody wants to be tied to a loser.

3. The Latino vote

Hispanics make up about 20 percent of the vote in Arizona but probably less than a quarter of those vote in the GOP primary. At the last GOP debate, Romney came out for HB1070, the odious Arizona immigration law that the federal government is challenging. Not that Santorum is any better on this issue. But 20 percent is the kind of margin that can tip a general election. In Arizona, it matters less who Latinos vote for today than if they show up at all. If they don’t, you know where they’re most likely gonna be come November. The Latino vote in Michigan, at 2 percent, matters less, but it’s also important: In 2008, Michigan’s Hispanics voted overwhelmingly for Barack Obama (67 percent).

4. Democrats

Democrats aren’t going to turn out in huge numbers, in spite of Santorum’s robo-calls and others urging them to cross party lines to mess with Romney. But if Romney doesn’t do as well as he should — whether he wins by a squeak or loses — watch for him to put the blame on the Dems. Conversely, don’ be surprised, should Santorum win, to hear him thank Democratic cross overs. It’s part of a campaign to make the case for his electability in November.

5. Paul Babeau

You know, the gay anti-immigration sheriff with the allegedly undocumented Mexican lover? He was Romney’s state co-chair and resigned the campaign post in the middle of a scandal, but that’s unlikely to translate into walk-aways from Romney. But watch Babeau’s own race for Congress in Arizona’s 4th Congressional District. If he wins — and say what you will about Babaeu’s closeted life, when he came out, he came out without apology — that will mean Congress will have a very out gay Republican among its members. That could be a real game changer for some in the GOP.