Welcome to FiveThirtyEight’s live blog of the Iowa caucuses.

The real action will not get under way until 8 p.m. New York time, when caucuses convene around the state — and it is likely to be at least another hour or so after that before we start seeing the first results. However, we will be entertaining you with various statistically driven observations before then, including data from entrance polls.

My updates will appear below, and also on the live Iowa caucus dashboard, which brings together updates and analysis from me and the Times political unit.



Various television reports suggest that Mitt Romney won the outstanding precinct in Clinton and has a lead of about 14 votes over Rick Santorum. But there is no official word yet from statewide Republican officials in Iowa about the outcome. It is also unclear whether there are any irregularities in the vote-counting that either Mr. Romney or Mr. Santorum’s campaign might seek to challenge. Nevertheless, as it is entirely unclear when and whether this will be resolved, we are shutting down this liveblog for the night. You can check out NYTimes.com or follow my Twitter feed for further updates. — NATE SILVER

And then there was one. A precinct in the town of Clinton in Clinton, County, Iowa will determine the winner of the Iowa caucus. Rick Santorum leads Mitt Romney by four votes statewide — 29,968 to 29,964 — according to the most recent count by the Republican Party of Iowa. Seven other precincts have voted in the town of Clinton. Four of them favored Mr. Romney over Mr. Santorum, two of them favored Mr. Santorum over Mr. Romney and the candidates exactly tied in the final one. — NATE SILVER

According to David Wasserman of the Cook Political Report, the outstanding precinct in Clinton County, which has slightly favored Mitt Romney tonight, had 422 John McCain voters in the general election of 2008. Based on the ratio of caucus-goers tonight to the number of votes for Mr. McCain in 2008, that would imply it has about 75 caucus votes outstanding. By the same method, the outstanding precinct in Keokuk County, which has the wonderfully Iowan name “Sigourney Plank Van Buren” and which might favor Mr. Santorum, should have about 30 caucus-goers. — NATE SILVER

The 18 votes separating Rick Santorum and Mitt Romney right now are fewer than the 49 received by Buddy Roemer. — NATE SILVER

According to Google and CNN, Rick Santorum leads Mitt Romney by 18 votes — 29,944 to 29,926 — with two precincts yet to report results. One of the precincts is in Keokuk County, which has slightly favored Mr. Santorum tonight, and the other is in Clinton County, which has slightly favored Mr. Romney. — NATE SILVER

A measly 34 votes separate Mitt Romney and Rick Santorum at the moment, with 99 percent of precincts reporting. It’s going to be extremely close no matter how that remaining 1 percent vote. So how’s this caucus compare to other primaries and caucuses in terms of tightness? Helpfully, the crack team over at Larry Sabato’s Crystal Ball put together a list of some particularly close calls from the past. Among the highlights: In 1980, Ted Kennedy edged Jimmy Carter in Pennsylvania by 0.3 percent, 45.7 to 45.4. In 2004 in Oklahoma, Wesley Clark beat John Edwards by a margin of just 0.4 percent, 29.9 to 29.5 (John Kerry, at 26.8, wasn’t too far behind either). In Minnesota in 1992, Bill Clinton topped Jerry Brown by 0.5 percent, 31.1 to 30.6. And tonight’s Republican caucuses may out slim all of the above; Mr. Santorum and Mr. Romney are currently just three hundreths of a percentage point apart. — MICAH COHEN

This is a little surprising to me. Despite Rick Santorum having achieved what is almost literally a tie for first in the Iowa caucuses, and another conservative candidate in Rick Perry likely to drop his campaign, Mr. Santorum’s chances of winning the Republican nomination are listed at 5.4 percent on Intrade, not much better than where they started the day, at 4 percent. — NATE SILVER

The most up-to-date vote totals appear to be from Google, which list Mitt Romney with 29,326 votes and Rick Santorum 29,277. Google has more precincts in from Story County than other sources. — NATE SILVER

Based on a county-by-county extrapolation of precincts that have yet to report, the final total would be Mr. Romney 30,286 votes, Mr. Santorum 30,201 votes. Needless to say, it may still be some time before this race gets called. However, even though Mr. Santorum has a very small lead right now, the remaining precincts look to be ever so slightly more favorable to Mr. Romney. — NATE SILVER

While Mitt Romney still only leads Rick Santorum by 13 votes with 92 percent of precincts reports, Mr. Romney has a moderate lead over at Intrade. His chances of winning Iowa are up to 64 percent (although they have been dropping recently). That’s 14 percent up from where he started the day. In fact, his odds have been on a roller coaster ride all day, bottoming out at 25 percent and rising as high as 95 percent. The contract on Mr. Santorum to win the Iowa caucuses now sits at 45 percent. That’s close to his high for the day (and he was as low as 6 percent). Meanwhile, Ron Paul, whose Intrade odds reached 50 percent the last time we checked in, is now at 0.1 percent — MICAH COHEN

We’ve seen slightly more voters per precinct in recent counties: there are now 114,483 votes counted, which should put us very close to 2008’s total of 119,000 Republican caucus votes and perhaps a little higher. — NATE SILVER

Meanwhile, there are two Iowa counties that have yet to report results at all: Madison County, which gave 44 percent of its vote to Mike Huckabee and 16 percent to Mitt Romney in 2008, and Monona County, which went 36-29 for Mr. Romney over Mr. Huckabee. Thus, Madison County would appear to be favorable to Rick Santorum and Monona County to Mitt Romney. Note, however, that Madison County is larger and cast three times as many Republican ballots in 2008. — NATE SILVER

Of some relevance to our last update: in 2008, Story County, which has the largest batch of precincts outstanding, gave 40 percent of its vote to Mike Huckabee, 23 percent to Mitt Romney and 13 percent to Ron Paul. — NATE SILVER

Story County, which contains the college town of Ames, remains the most sluggish to report results tonight. Just 1 of its 43 precincts are in so far, which means that it accounts for about one-fifth of the remaining vote in Iowa. Ron Paul won the only precinct to report in the county so far with 57 percent of the vote to 17 percent for Rick Santorum and 14 percent for Mitt Romney. However, with the statewide race now looking as though it will come down to Mr. Santorum and Mr. Romney, the question is which of those two might be expected to perform better. Of note is the fact that Mr. Romney performed considerably better than Mr. Santorum in Johnson County, where Iowa City is located, although Iowa City’s politics are more liberal than those of Ames. — NATE SILVER

The county with the most uncounted precincts is Polk County, which contains the state capital of Des Moines. Although 67 precincts have reported their results there, another 116 have not. However, it may not go very far toward resolving the near-tie between the top three candidates: Ron Paul has 25 percent of the vote there, Rick Santorum 24 percent and Mitt Romney 22 percent. — NATE SILVER

The funniest candidate reaction of the night so far goes to former Gov. Buddy Roemer of Louisiana. Mr. Roemer is currently in last place with 9 (that’s votes, not percentage points), but, rolling with the punches, he tweeted: I almost have enough votes in Iowa to start a bowling league. #Roementum — MICAH COHEN

Although Ron Paul has fallen slightly behind Rick Santorum and Mitt Romney in the vote-counting, he still has a chance of winning — in part because some of his strongest areas, college towns, have been slow to report results. Story County, where Iowa State University is located, has had none of its 43 precincts report. And only 22 of 57 precincts have reported in Johnson County, home to the University of Iowa. (Mr. Paul has 36 percent of the votes there so far.) — NATE SILVER

Remember when we reported earlier that Ron Paul had an early lead in entrance polls with evangelical voters — but cautioned that early entrance polls are often unreliable? There are now several more waves of entrance poll data in, as well as some actual voting results to help calibrate them. Based on this much-improved data, the entrance polls now estimate that Mr. Paul received 19 percent of the evangelical vote — well behind Rick Santorum’s 32 percent. — NATE SILVER

With 842 out of 1,774 precincts reporting so far, 54,223 Iowans have cast ballots in the Republican caucuses. A linear projection would estimate the total number of votes at 114,429, slightly behind the 119,118 who voted in 2008. So far, reporters who observed that there did not seem to be huge waves of enthusiasm at the events held around Iowa look to be vindicated. — NATE SILVER

It’s still early, but it appears the eventual winner in Iowa tonight may end up with a somewhat dubious distinction: the smallest share of the electorate by any winner. That title to date is held by Bob Dole, who won the Republican caucus in Iowa in 1996 with 26 percent of the vote (that was, as Nate said, the closest Iowa caucus in history). Right now, no candidate has more than 24 percent.

On the Democratic side, the Iowa winner with the smallest percent of caucus support was Richard Gephardt. He notched 31 percent in 1988. That year, Paul Simon finished second with 27 percent and Michael Dukakis finished third with 22 percent.

— MICAH COHEN

About half the counties west of Des Moines have yet to report any results, a potentially good sign for Rick Santorum, since he has led the vote in most of western Iowa so far. Southern Iowa, where Ron Paul is running well, has also been slow to report results. — NATE SILVER

Although it’s still far too early to project the results, much less the spin that will result from them, my column this morning suggested an optimal scenario for Jon M. Huntsman, Jr: In particular, Mr. Huntsman might be hoping for a highly ambiguous finish, especially an effective three-way tie as is projected by the current polling, and which 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. This is pretty much exactly what we’re seeing based on the votes counted thus far. — NATE SILVER

The results in Boone County in west-central Iowa, one of the first to report all its votes, help to explain why the contest is so close tonight. Mitt Romney underperformed his 2008 vote share in the county, taking 17 percent of the vote as opposed to 21 percent. Rick Santorum, although he won the county, did not perform as well as Mike Huckabee did in 2008, taking 30 percent of the vote to Mr. Huckabee’s 42. Imagine that Mr. Romney underachieves his 2008 vote share by 4 points statewide, as he did in Boone County. Mr. Romney would then finish with 21 percent of the vote. Meanwhile, if Mr. Santorum underperformed Mr. Huckabee’s vote share by 12 points statewide, as he did in Boone County, he would finish with 22 percent of the vote. Everything we are seeing points to an incredibly close finish; I don’t think this is a fluke based on the counties that happen to have reported so far. — NATE SILVER

Daniel Acker for The New York Times With fewer than 300 votes separating first-place Ron Paul from third-place Mitt Romney in votes counted so far, it should go without saying that we may be headed for a photo finish. The closest caucus historically came in 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. — NATE SILVER

I don’t perceive a big edge for any of the three leading candidates in results or entrance poll data so far — but bettors at Intrade like what they are seeing for Ron Paul. He is now given a 50 percent chance of winning by the betting market, up from about 30 percent this morning. — NATE SILVER

The Iowa country with the largest share of the vote counted so far is Cedar County, in eastern Iowa between Cedar Rapids and Des Moines. More than half of its precincts have reported. It’s not an especially populous county so interpret this cautiously, but Mitt Romney so far only has 22 percent of the vote there — well behind the 35 percent he took there in 2008. — NATE SILVER

Entrance polls and very easy voting tabulations don’t always tell you much about who is winning — but they can tell you something about who has too steep a hill to climb. So far, that candidate appears to be Michele Bachmann. She has just 6 percent of the vote in the first 49 precincts that reported, even though other conservative candidates are performing well in these areas. And her entrance polls are no better: she was favored by only 8 percent of evangelical voters, for instance.

Another key finding in the entrance polls so far: almost 30 percent of voters identify as either independent or Democratic, much higher than in 2008 and toward the high range of the estimates that pollsters made in their likely voter models. The entrance polls report that about half of those voters are breaking for Ron Paul. Likewise, the percentage of moderates according to the the exit polls is about 20 percent — twice as high as in 2008 — and those voters so far are breaking for Mr. Paul as well. — NATE SILVER

The proportion of evangelical voters in the initial wave of Iowa entrance polls is quite high — 58 percent — more than most pollsters projected, although similar to 2008. That would seem like a good omen for Rick Santorum’s campaign. But so far, the candidate leading among these voters is Ron Paul. Keep in mind, however, that the entrance polls are a very rough guide. Not only may the samples be unrepresentative — minds can also be changed once voters are inside the caucus site. — NATE SILVER

One of the parlor games that analysts play while awaiting voting results is to anticipate whether reports of strong or weak turnout will play to the benefit of one or another candidate. One common sentiment this year, for instance, seems to be that high turnout would be a good sign for Mitt Romney, and low turnout a good omen for Rick Santorum. I would urge some caution here — the interpretations are not always so straightforward. In 2008, for instance, Mike Huckabee — the candidate to whom Mr. Santorum bears the greatest resemblance — won the caucuses with record-high turnout, appealing to evangelicals who had not caucused before. Or what about a candidate like Ron Paul? Is high turnout a good sign for him because it implies that he is extending the electorate to new voters like independents? Or would he prefer low turnout because it means that only the most enthusiastic voters are turning out — and Mr. Paul’s supporters tend to be more enthusiastic than most others? You can make the case either way. Moreover, estimates of turnout based on anecdotal reports can often prove to be inaccurate later on. It will be more useful to look at where voters are turning out. A big turnout in the suburbs of Des Moines could help Mr. Romney. A big turnout in college towns like Iowa City and Ames could help Mr. Paul. Mr. Santorum would love a big turnout in rural areas, especially in western Iowa. — NATE SILVER

We’ll soon have real results from actual Iowan voters — not just likely or registered or imaginary — but for a long time now those craving data points have been dependent mostly on polls, which have been largely responsible for shaping expectations heading into tonight. Since the start of 2011, we’ve added almost 70 polls to the FiveThirtyEight polling database that asked about the Republican caucus in Iowa. Indeed, the state has been packed with pollsters: 23 different polling companies have been in the field in Iowa this year. Of the Iowa polls we have, about one-third were done over the phone with live interviewers, while the rest were automated. In all, 38,097 Iowans deemed likely to vote were surveyed about the G.O.P. race (give or take). That’s about a third of the total turnout in the state’s 2008 G.O.P. caucus, although this year more are expected without a contested Democratic caucus to compete against. — MICAH COHEN

Megan Liberman and Nate Silver talk about what we might expect to see and what unexpected outcomes to look for in the Iowa Caucus tonight.

Politico’s Mike Allen suggested in Playbook this morning that despite the razor-close polling in Iowa, most members of the news media expect Mitt Romney to win the caucuses tonight. Now we have some hard evidence for that. ABC News bravely asked its reporters and correspondents to predict the winner in the caucuses. Nine of them select Mr. Romney, compared to just two votes for Ron Paul and two for Rick Santorum. None of the correspondents, meanwhile, expected Mr. Romney to finish below second place. Since managing expectations is half the battle in Iowa, this is not necessarily a vote of confidence that Mr. Romney’s campaign will appreciate. Then again, Mr. Romney’s campaign has taken a more confident posture toward its projected finish in recent days. This will all be water under the bridge if Mr. Romney wins tonight — or finishes in a clear second place — but will look like an unforced error if he finishes third or worse. — NATE SILVER