The Iowa poll the political world has been eagerly awaiting is finally here — and it has great news for Donald Trump.

On Saturday evening, Bloomberg Politics and the Des Moines Register released the results of their final Iowa caucus poll, which is conducted by widely respected pollster Ann Selzer and has been extremely accurate in recent years.

For the Republican race, the poll found Trump in first among likely caucus-goers with 28 percent, Ted Cruz in second with 23 percent, and Marco Rubio in third with 15 percent. Ben Carson is in fourth with 10 percent, and no other candidate gets more than 5 percent support.

On the Democratic side, Hillary Clinton is ahead with 45 percent among likely caucus-goers, followed by Bernie Sanders with 42 percent. Martin O'Malley is very far back, with just 3 percent.

In a live event announcing the poll results, Selzer said there was no indication that Thursday night's GOP debate (and Trump's failure to attend it) led to any serious movement in the numbers.

Selzer has a very good track record of polling the caucuses

Polling the Iowa caucuses is extremely difficult. These events aren't like ordinary primaries — they take place at a specific time in the evening and can last hours. So predicting who will show up is extremely difficult, and has led many pollsters astray in the past. Plus, many voters end up deciding quite late, so it's a challenge for a pollster to detect if any one candidate suddenly surges in the final days.

Selzer, though, seems to be an expert at both modeling turnout and picking up on this late movement, as her track record shows:

In 2004, her final Democratic poll showed both John Kerry and John Edwards suddenly surpassing the previous poll leader, Howard Dean — which is just what happened.

In 2008, when everyone else's final Democratic polls were mixed, she went against the grain by finding Barack Obama up by 7 percentage points — and then he won by 7.8 points. She called the Republican winner that year, Mike Huckabee, too.

In 2012, her final Republican poll showed the eventual winner (Rick Santorum) in third place. But Selzer did make sure to note that Santorum's support suddenly started surging midway through her interviews, saying, "I have never seen such a dramatic change over four days of interviewing." So insiders who read the poll closely were well-prepared to expect Santorum's triumph.

Trump's lead is bigger than Clinton's

The biggest remaining question about Donald Trump's campaign has long been about whether his supporters would actually turn out to the polls — and especially to the caucuses.

But if Selzer's numbers are any indication, the race has tipped toward Trump in recent weeks (her poll has previously shown Cruz up). The billionaire whose presidential ambitions have long been mocked, scorned, and dismissed seems well-positioned to pull off a historic victory in Iowa Monday night — one that, if it transpires, will surely lead to a media frenzy that could boost his numbers elsewhere too.

As for Marco Rubio — long believed to be the GOP establishment's best hope — the Floridian still appears to be well behind Trump and Cruz. Chatter about a Rubio surge in Iowa in the final days appears to be exaggerated, at least according to Selzer's numbers.

On the Democratic side, Hillary Clinton is surely very relieved that Selzer's numbers still show her leading Sanders. In recent weeks, it's seemed quite possible that she could lose both Iowa and New Hampshire — which would have been an embarrassing defeat for the supposedly inevitable Democratic nominee.

But the poll only shows Clinton up by 3 percentage points — less than Trump's lead. So it's a very tight race, and any number of things — news stories, turnout operations, enthusiasm, weather — could swing the results in the final days. Expect a nail-biter on Monday night.