Mitt Romney has now moved into a tiny lead in Ohio, the first time since early this evening. But here’s another thing to watch. In Ohio, a candidate has to win by more than .25% of the vote to avoid a mandatory recount. In practice that means the victory has to be more than about 2,000 votes. That’s just about where Romney is right now.

So there’s who has the most votes tonight but there’s also the margin the candidate needs to avoid a mandatory recount.

AP still shows a Santorum lead of just under 3,000 votes. But live reports from the counters in the key counties seem to suggest Romney can pick up enough to pull it out.

Another round of exits just came in in Ohio. And it’s dead even.

For context, first round was Romney +4, just before 8 PM it was Romney +1.

Even by the standards of political campaigns, Newt Gingrich’s bogus attack on President Obama tonight was breathtaking.

For first time in a while, Romney’s closing the gap with Santorum. 47% precincts in: Santo 38.3%, Romney 36.4%.

As of this moment, we have 37% of the precincts reporting. And Santorum is up by 3.2%. That’s just shy 17,000 votes. But what’s left in the remaining 63% of precincts. The key is that what’s to come is almost certainly better for Mitt than what we’ve seen so far, mainly becomes a lot of Republican-leaning suburbs are lagging behind the vote count. But is it enough? Nate Silver seems to think it may not be and that Santorum — based on all the data before us right now — is the slight favorite. That sounds right to me, especially because Nate seems to think so too.

Mitt Romney’s about to speak tonight. Very curious to hear what he says since so far tonight he’s yet to win a major contested primary. My hunch is he just ignores the returns and gives the general election speech.

For the moment, Santorum has a 2 point lead over Romney in Ohio. That’s with 18% of precincts reporting.

So far, Rick Santorum has scored a big win in Tennessee and at least a win (according to projections just coming in from the nets) in Oklahoma. The current numbers show a close race in Ohio. But the most recent exit poll from about an hour ago shows Romney winning by a single percentage point in Ohio. That means Romney probably wins there, more likely than not.

If he does it’s not a great night because he lost in Oklahoma, Tennessee and Georgia. But if he loses Ohio, which does not look likely but definitely still possible, it’s a catastrophic night for Mitt.

The latest round of exit polls just came out of Ohio and they now show Romney with just a one point advantage. So this could get interesting.

8:02 PM: To give you some context here, the first exits out this afternoon showed Mitt +4. That helped shape some of the coverage as well. The latest exits were Mitt +1. That’s a lot better for Mitt than -1. But that means that Santorum is still in it in Ohio and the numbers I’m seeing show him (Santorum) doing really well in Tennessee.

8:38 PM: Santorum wins Tennessee.