3:10 a.m.: The state GOP has announced that Romney won by a mere eight votes. But this finish is "so close that statistics majors at Iowa State will probably see it as a question on the final," says John Dickerson at Slate. All that matters now, says Jonathan Bernstein in The Washington Post, is "the spin over the next few days, and it doesn't seem to me that the exact order of finish will affect that very much."
1:38 a.m.: "One vote!" declares an amazed Wolf Blitzer on CNN. Indeed, Romney now leads Santorum 29,957 votes to 29,956 votes. "Bless you, Iowa," tweets Reuters' Sam Youngman. "A boy couldn't ask for much more" than this fantastic race.
12:59 a.m.: It's still too close too call, says CNN. With nearly every single precinct reporting, Santorum has a 19-vote lead over Romney. But take heart, tweets the New York Daily News' Josh Greenman. "Second prize is a set of steak knives."
12:50 a.m.: "Oh Jesus," tweets Salon's Joan Walsh during Romney's speech. "He's repeating his America the Beautiful lines, corn-jokes and all. Mitt, this is a disaster."
12:45 a.m.: Now it's Mitt's turn. "Santorum spoke from his heart," tweets Paul Begala at the Daily Beast. "Not to be outdone, Mitt is speaking from his CPU." Indeed, this is nothing but a "straight Romney stump speech," tweets The Washington Post's Chris Cillizza.
12:37 a.m.: With 99 percent of precincts reporting, Santorum has a razor-thin five-vote lead over Romney. And that's not the only impressive thing, tweets Slate's John Dickerson. "Santorum's speech is better than anything I've ever heard Romney give."
12:20 a.m.: Santorum just took the stage to deliver his victory speech, and got "very, very emotional praising his wife," tweets Fox News' Ed Henry. "This is his moment & he's hitting it out of park."
12:15 a.m.: Sure, the votes are still being counted. But Santorum blew it by not delivering a stemwinder earlier this evening, tweets The Daily Beast's Howard Kurtz. The little-known conservative "missed a chance to introduce himself to America before it went to sleep. Should have come out and declared victory."
12:09 a.m.: "Rick Perry is the worst presidential candidate in American history," James Carville declares on CNN, moments after the Texas governor all but drops out following his fifth-place finish in Iowa.
12:06 a.m.: "Perry's making the right call after finishing fifth and as far back as he did," tweets TheWeek.com columnist Ed Morrissey. "Bachmann should get the hint and do the same."
12:03 a.m.: We may not have Rick Perry to kick around anymore. "I have decided to return to Texas," Perry just announced, to "determine whether there is a path forward for myself in this race." Look, tweets Politico's Jonathan Martin, "once a candidate signals uncertainty, the voters bail. See Cain, Herman." Yeah, tweets Political Wire's Taegan Goddard. "Perry is essentially dropping out and Gingrich has new life."
11:48 p.m.: With 96 percent of the precincts reporting, Rick Santorum leads Mitt Romney by 113 votes. "Does every freakin' election have to go down to the wire?" tweets Daily Kos' Markos Moulitsas.
11:45 p.m.: Why is everyone impressed with Newt's speech? asks W. James Antle, III at The American Spectator. "The moments of petulance undermined the moments of grace. It was a stark reminder of the personality traits that led Republican voters to reject him in the first place."
11:29 p.m.: Newt's fiery speech just ended with a snippet from "Eye of the Tiger." Gingrich was "on fire," tweets CNN's Donna Brazile. He's clearly "determined to regain his frontrunner status and eager to fight the next battle. This will be fun!" Yeah, watch out, tweets Politico's Glenn Thrush. Newt may be "turning the most dangerous mouth in politics on Mitt."
11:25 p.m.: Newt Gingrich is delivering a speech in which he praised Rick Santorum for running a positive campaign. He then implicitly zinged Mitt Romney: "I wish I could say that for all the candidates." Ouch, tweets The Washington Post's Chris Cillizza. "Newt is BITTER at Romney. Is a kamikaze mission far off?"
11:14 p.m.: Santorum and Romney are still duking it out for first, but CNN projects that the rest of the field is set: Ron Paul finishes in third, Newt Gingrich in fourth, Rick Perry in fifth, Michele Bachmann in sixth, and Jon Huntsman, who didn't compete in Iowa, in seventh. "Over the long term, who lost big in Iowa may mean more than who won," says Ron Fournier at National Journal. "The two biggest threats to Romney finished out of the running: Former House Speaker Newt Gingrich and Texas Gov. Rick Perry." That means Romney is still "the odds-on favorite to win the Republican presidential nomination."
11:05 p.m.: A mere 13 votes separate Romney and Santorum. But regardless of who finishes on top, tweets The Washington Post's Chris Cillizza, Santorum, who came from nowhere, is the clear winner tonight. And he better get ready for some scrutiny, tweets Mother Jones' David Corn. "Mr. Santorum, here is a helmet, a flak jacket, and a roll of bandages. Buckle up, sir."
10:55 p.m.: So much for an enthusiastic GOP, says Nate Silver at The New York Times. Turnout may be lower in 2012 than it was in 2008. "Reporters who observed that there did not seem to be huge waves of enthusiasm at the events held around Iowa look to be vindicated."
10:52 p.m.: Fox News projects that Rick Perry will finish fifth behind Newt Gingrich, says Allahpundit at Hot Air. "He spent $6 million in the state for this; one of the subplots of the coming week will be whether he should drop out and endorse Santorum or Gingrich in order to try to stop Romney." Let's face it, says Andrew Sullivan at The Daily Beast: "Perry is one of the most embarrassingly awful candidates for a national party since Sarah Palin. He should quit but won't."
10:50 p.m.: What a nailbiter, says Wolf Blitzer on CNN. With 88 percent of the vote counted, Rick Santorum leads Mitt Romney by a miniscule 45 votes. Amazing.
10:29 p.m.: It's too soon to guess the winner, but so far "the general result looks like a clean divide between those favoring libertarianism, Christianism, and Romneyism," says Andrew Sullivan at The Daily Beast. "So take your pick:" Paul, Santorum, or Mitt. The losers are easier to see, says Jennifer Rubin at The Washington Post. "Rep. Michele Bachmann (R-Minn.) appears headed for sixth. She in all likelihood ends her race in her home state on Feb. 7. Texas Gov. Rick Perry may well wind up in fifth, even after spending $4 million, leaving a real question as to whether he should soldier on."
10:14 p.m.: With 48 percent of the vote counted, Rick Santorum leads with 24.3 percent, with Romney (23.7 percent) and Paul (21.8 percent) close behind. "Does it matter who wins, when it's this close?" asks Andrew Sullivan at The Daily Beast. "Of course, there's a bump from any actual victory. But if I were Romney, I wouldn't want to come in third, especially if he gets fewer votes this time than in 2008. Nonetheless, it seems to me that Santorum's late surge has hurt Paul and denied him what would have been a stunner. Bachmann is surely toast; Perry has long since become a joke; and Gingrich has shown how vulnerable he is to Super-Pac sliming."
10:09 p.m.: Tonight's three-way tie may play right into Jon Huntsman's hands, says Nate Silver at The New York Times. "A highly ambiguous finish... would leave no candidate with demonstrable momentum. That would free up news bandwidth for him in New Hampshire, where his polling is stronger but where he will have to compete with several other candidates for attention. The less news coming out of Iowa, the more time the news media will have to speculate about whether it is finally Mr. Huntsman's turn to surge."
10:01 p.m.: "Remind me again," says Allahpundit at Hot Air. "Now that we know who the top three will be and that it'll be very close, what does it matter what the order is? If Romney finishes third, that'll be good enough for a tepid 'is Romney underperforming?' narrative this week, but it does nothing to answer the question of who's supposed to emerge from the field and beat him in the long slog to the convention."
9:56 p.m.: Remember all those Mitt Romney-Hillary Clinton comparisons? Well, tweets Huffington Post's Sam Stein, it's also "worth recalling that H Clinton finished third in Iowa. Her handling of the state was kinda, though not entirely, similar to Romney's."
9:50 p.m.: With the libertarian Paul doing so well, tweets Mother Jones' David Corn, I wonder if a President Romney would "have to offer Ron Paul a position, say, Secretary of Smashing Government?"
9:45 p.m.: With 30 percent of the vote counted, Romney leads with 23.1 percent, with Paul (23.0 percent) and Santorum (22.9 percent) nipping at his heels. "Pretty amazing," tweets Talking Points Memo's Josh Marshall. Indeed, this may wind up being the closest Iowa caucus ever, says Nate Silver at The New York Times. Previously, that honor went to 1996, "when Bob Dole finished with 26 percent of the vote, Pat Buchanan 23 percent, and Lamar Alexander with 18 percent. The 8-point gap separating Mr. Dole and Mr. Alexander may wind up being much larger than the margin separating the top three candidates tonight."
9:38 p.m.: "The Republican Party is seriously fractured," says Taegan Goddard at Political Wire. "Each of the leading three candidates represents a very different segment of the GOP."
9:35 p.m.: Nearly a quarter of the votes have been counted, and Ron Paul is in a virtual tie with Santorum and Romney. But "Paul is just roasting the others among moderates and liberals, who showed up in huge numbers for the express purpose of voting in Ron Paul," says Jim Newell at Gawker. "I didn't think the Paul campaign could successfully get everyone off the computer for a night. But could the rumors of the indestructible beast that is the Paul organization be true? Are libtards and children and moddies going to win the Republican Iowa caucuses for a candidate that a majority of Republicans consider their enemy? That's not going to fly in national Republican HQ atop Death Mountain. Bye bye, Iowa caucuses!"
9:20 p.m.: With 16 percent of the votes counted, less than 200 votes separate Ron Paul, Rick Santorum, and Mitt Romney. "If Santorum finishes third but close," tweets TheWeek.com columnist Ed Morrissey, "is that enough for him to get donors and keep going?" No, tweets Mother Jones' Clara Jeffery. "PEOPLE!! Santorum will never, ever be the nominee. GOP base, spare yourself the heartache." Indeed, tweets ABC's Rick Klein. "A three-way jumble at top is Romney win. Especially when jumble included weaker candidates."
9:07 p.m.: Why are so many young voters breaking for Ron Paul? My generation, tweets National Review's Dan Foster, is "still naive enough to believe that politics can be outlawed."
9:00 p.m.: With 6 percent of the vote counted, Romney is in third, a showing that many pundits believe would embarass the slow-and-steady frontrunner. But if he "comes in a close third," tweets Outside the Beltway's Doug Mataconis, "behind two men who have no chance of winning the nomination (Paul and Santorum) that's a good night."
8:56 p.m.: How the mighty have fallen, says Steve Benen at Washington Monthly. "Several of the news networks are projecting that Bachmann will finish last tonight... Remember when Bachmann won the Ames Straw Poll? Well, August was a long time ago."
8:45 p.m.: According to CNN's entrance poll, notes David Weigel at Slate, "Paul cleans up with 'liberal or moderate' voters, winning 40 percent of them, and wins 48 percent of independents." That supposedly damaging story about allegedly racist newsletters sure doesn't seem to be hurting the Texan.
8:29 p.m.: A key question, tweets CNBC's John Harwood. If Santorum, who's in a strong third in CNN's entrance polls, "rockets out of Iowa: Will rich friends like banker/Catholic philanthropist Frank Hanna of Atl write fat SuperPac checks?" That would really help Santorum capitalize on his Hawkeye State momentum.
8:11 p.m.: The caucuses have officially begun, and early entrance polls show Romney and Paul in a dead heat. They also show that Iowa's 2012 "electorate is older and with more indies/moderates than 2008," tweets The Washington Post's Chris Cillizza. If that's true, tweets Politico's Glenn Thrush, it's good news for Romney, who polls well with older voters, and bad news for Paul, who excels with young voters. Maybe, says Ari Fleischer on CNN, but if those independent voters side with the Texas libertarian, they could "be the secret to Ron Paul's success tonight."
7:45 p.m.: "If Santorum wins," says Erick Erickson at RedState, "a lot of people will be correct in saying Mitt Romney is still a winner because Santorum has no money or real organization to go beyond Iowa. But my God in Heaven, the media is finally going to be confronted with an 'Emperor Has No Clothes' moment on Romney." He's supposedly "the most electable" candidate — but barely one-fourth of the party supports him.
7:26 p.m.: "Here's the thing," tweets Reuters' Sam Youngman. Michele Bachmann, who is at or near dead last in the polls, "is from here. I mean born and raised here. If she can't do well here, where can she?"
7:18 p.m.: ABC News "bravely asked its reporters and correspondents to predict the winner" in Iowa, says Nate Silver at The New York Times. "Nine of them selected Mr. Romney, compared to just two votes for Ron Paul, and two for Rick Santorum." But "this is not necessarily a vote of confidence that Mr. Romney's campaign will appreciate." Remember, in Iowa, "managing expectations is half the battle." With many pundits predicting a Romney win, Mitt will disappoint if "he finishes third or worse."
7:00 p.m.: Tonight's the night. Just an hour from now, tens of thousands of Iowa Republicans will gather to caucus, officially kicking off the 2012 presidential nominating contest. To get you started, here are seven key questions that will be answered tonight, a guide to the caucuses' "idiosyncratic" rules, and a primer on why exactly Iowa matters. Stay tuned — we'll be live-blogging the opinion as the results roll in.