Polls close at 8 p.m. ET. Hey, remember six days ago when this was going to be Santorum’s last, best chance to steal a major “Romney state” away from Romney (in the midwest, no less) and make a real race of this thing? According to the pollsters, that chance has come and gone. I wonder why.

As much as I enjoy the all-night election threads, looks like we’re destined for this one to be called promptly at eight. Exit polls and video of the speeches will follow below but no cliffhangers tonight, alas. Ask not for whom the bell tolls, says Nate Silver — it tolls for Sweater Vest:

In fact, Mr. Santorum now looks like he’ll win no more than a third of the 54 delegates that are at stake on Tuesday. Illinois awards its delegates entirely by Congressional district — two to four at a time. If Mr. Santorum is losing the state by 10 or more points, he is unlikely to win any of the 12 Congressional districts that are divided between Chicago and its suburbs. And he has no chance at all of winning the 13th Congressional District, which is more favorable to him but where he failed to get enough signatures to get his delegates on the ballot…

Say that Mr. Romney wins the 16th Congressional District, which includes some areas on the far outskirts of the Chicago metro area, but Mr. Romney holds the other four. That would make the delegate count for the night Romney 40, Santorum 14, and put Mr. Romney ahead by almost 300 delegates — 561 to 267 — in the national total.

That isn’t a close race, nor is it one that it is likely to require a brokered convention to resolve. If that is the count after Illinois votes, Mr. Romney would require only 46 percent of the remaining delegates to clinch a majority (he was won about 55 percent so far), and only 39 percent to clinch a plurality.

Per Jeff Greenfield, there may be one last path left to deny Romney the nomination. Change the rules:

If Romney has not secured the nomination by the time the delegates convene in Tampa, Fla., at the end of August, the prospects for a genuine floor fight are greater than you might imagine. The reason is that delegates who are bound or pledged to a candidate are only obligated to follow his wishes when it comes to voting for a nominee. And in most contentious conventions, it is a fight over the rules that has effectively determined the nominee…

Suppose the challenge to Romney is broader, and that, like the Kennedy forces did in 1980, the opposition offers a rule to free all the delegates from their commitments on the ground that the primaries have demonstrated Romney’s weakness. Here, we could see a number of delegates bound to Romney vote to liberate themselves from the obligation to vote for him. (Again, we should note that delegates bound to vote for Romney as the nominee don’t have to side with him on other votes that stand to determine his fate.) Sure, most delegates would probably stand by the former governor on grounds of loyalty, fairness or fear of reprisals. But if Romney has not garnered a large enough share of delegates by convention time, it would not take many defections to make every delegate a free agent, and thus turn the whole convention upside down.

Maybe, but don’t forget that there are 123 superdelegates in the mix too, the vast majority of which are likely to break for Mitt in the interest of avoiding a floor fight if he shows up in Tampa on the cusp of 1,144. If he rolls out a pledge from, say, 100 superdelegates to back him and that puts him over the top, how likely is it that the other delegates will refuse him a nomination that he’s essentially clinched?

Here’s CNN’s Illinois election page for real-time results. You know the drill by now: Metro areas (i.e. Cook County and its surroundings) belong to Team Mitt, rural areas belong to Team Sweater. Whoever overperforms in the other’s stronghold will have a good night. Updates to come below. Exit question one: Can Romney hit 50 percent? If so, I wonder if he’ll use his victory speech to formally call on Santorum and Gingrich to drop out. If not, expect the media narrative tomorrow to look something like this. Exit question two: How much longer can Newt hold on? He already has as much campaign debt as cash on hand and the donations are drying up.

Update: Michele Bachmann: “At this point, we would be better off if we could unify around a candidate, whoever that candidate may be.”

Update: Preliminary exit polls already looking good for Romney:

Preliminary exit poll results find that six in 10 Illinois voters see Romney as the candidate with the best chance of beating Barack Obama, a bit better than his average across exit polls this year. More strikingly, Romney also leads Rick Santorum, albeit narrowly, as the candidate who “best understands the problems of average Americans.”

It’s only the second state, of six where the question’s been asked, in which Romney’s been poised to beat his rivals on empathy. The other was Florida.

Update: Here’s the exit poll promptly at 8 p.m. No call yet, but assuming the exits are right, Romney wins by 10 points with 45 percent of the vote. Back with highlights in a moment.

Update: Demographics have been destiny so far in the primaries and Illinois is no different. Scroll through the exits and you’ll see lots of familiar trends: Santorum wins voters with no college education while Romney wins college grads and up; Santorum wins lower-income voters while Romney wins the rich; Santorum wins the “very conservative” while Romney cleans up with centrists and independents; Santorum dominates among evangelicals while Romney dominates among non-evangelicals; Santorum crushes Romney among those who say it’s most important that the candidate’s a “true conservative” while Romney crushes Santorum on electability. Two interesting outlier data points, though — and bear in mind that the exit numbers will change slightly over the course of the evening as more data comes in. First, Mitt Romney, the tea party choice?

And second, Mitt Romney, the Catholic choice — in a landslide:

And then there’s this. When I first looked at the exits, it broke 48/40 for Mitt. As CNN’s refined the data, it’s shrunk:

That supports the conventional wisdom on Newt dropping out. Santorum closes the gap, but not enough to win. And Romney actually picks up a few votes, which puts him a tiny bit closer to winning a majority of delegates.

Update: At 8:33, the FNC decision desk says it’s all over. Now we wait for the speeches and to see how close Romney gets to 50 percent.

Update: Just got a blast e-mail from Team Newt. No gracious concession tonight:

“To defeat Barack Obama, Republicans can’t nominate a candidate who relies on outspending his opponents 7-1. Instead, we need a nominee who offers powerful solutions that hold the president accountable for his failures. Over the past few weeks, my $2.50 gas plan has shown how America could have cheaper gas, more jobs and greater national security while putting the White House on the defense over their anti-American energy policies. This is the type of leadership I can offer as the nominee, and this campaign will spend between now and when the delegates vote in Tampa relentlessly taking the fight to President Obama to make this case.”

Update: Here’s your tweet of the day from Newt, who’s dead last in Illinois as I write this — behind even Ron Paul:

Low turnout tonight. A nominee that depresses turnout won’t beat @BarackObama. Still time for a conservative. Join us

Update: Don’t look now, but with 53 percent reporting, not only is Romney outperforming the exit polls, he’s tantalizingly close to 50 percent. Right now he leads Santorum 48/34.

Update: Here’s Romney’s speech; read the corresponding NBC analysis for data points on why this might, might, might finally be proof that Republicans are grudgingly coming around to him. With the possible exception of Florida, this is the biggest win of his campaign. Next up: Wisconsin.

Visit msnbc.com for breaking news, world news, and news about the economy