Here's Which Democratic Candidate the Polls Predict Will Win Iowa as Caucus Begins

The 2020 election's early-voting season officially kicks off Monday evening as Iowans pick their preference for the Democratic Party's presidential nominee.

Joe Biden, Pete Buttigieg, Elizabeth Warren and Bernie Sanders have been wrestling for the top spot in the battleground state for months. But the latest survey shows Sanders surging among likely caucusgoers just ahead of Monday's vote.

An Emerson College poll released Sunday night found the Vermont senator leading the Democratic primary field by 7 percentage points, with 28 percent support in Iowa. Biden followed with 21 percent support, while Buttigieg and Warren trailed in third and fourth places, respectively, at 15 percent and 14 percent.

In an average of all the recent Iowa caucus polls, Real Clear Politics also shows Sanders ahead of his Democratic rivals. Prior to Monday's voting, RCP shows Sanders beating Biden by 4 percentage points. He's also leading against Buttigieg and Warren, by nearly double digits.

In his final pitch to Iowans on Sunday, Sanders focused on a unifying message that targeted President Donald Trump. He told voters, "No matter what your politics may be, I think we all understand that this is not the kind of person who should remain in the White House."

He also predicted that Monday's caucus will be "the beginning of the end for Donald Trump."

But this does not mean Sanders has the party's competitive race locked down. Polls have shown him and Biden as neck and neck in the state for weeks, and a CBS/YouGov survey released Sunday showed the two tied at 25 percent among likely caucusgoers.

Plus, Biden could pull ahead during the second alignment phase of the caucus. In Iowa, if a candidate doesn't get at least 15 percent support, the attendees who voted for that candidate have to shift to another contender. According to the latest Monmouth University poll, the former vice president is the top second-choice candidate for most Iowa voters.

Just outside the leading pack of candidates is Minnesota Senator Amy Klobuchar. In the latest Emerson poll, Klobuchar came in fifth, with 11 percent support. She was the only other candidate to have double-digit support in the state. The survey, conducted from January 30 to February 2, polled over 800 Iowans who were likely to participate in the Democratic caucuses. The margin of error for the poll is roughly 3 percentage points.

There was supposed to be one more key survey, from The Des Moines Register and CNN, ahead of Monday's caucus, but the outlets decided to scrap its release due to a technical error. The highly anticipated poll, which has been conducted for the past 76 years, is considered one of the best surveys for the hard-to-predict state.

The cancellation of the survey appears to be due to concern from Buttigieg's campaign that the former South Bend, Indiana, mayor was left off the candidate list for one question. In an editorial, the newspaper said the situation could not be confirmed but "out of an abundance of caution" it decided not to release the findings.

The Iowa caucuses begin at 7 p.m. CST.