DES MOINES, Iowa (CNN) -- This presidential cycle has been full of twists and turns, but there's been one constant: Conventional wisdom has been dead wrong.

In a year full of surprises, Donald Trump has upended the political norms. So as voters head to the Iowa caucuses Monday night, the only safe prediction is that the old rules may not apply.

Here's how we arrived at this unexpected moment in the race:

Donald Trump defies political gravity

It would be impossible to count the number of times this cycle that Trump has proved the political pundits wrong and surprised the nation with his moves.

First, many of us thought he would never enter the race. Then everyone said his rise in the polls was an anomaly. The political establishment assumed he'd be a passing fad -- and that Republican voters would ultimately move on to more "serious" candidates.

None of that happened.

His supporters have proven loyal and unwavering, and the race here in Iowa looks very tight. The question since it's this close, is what will Trump do to win?

He caused an uproar last week by pulling out of the Fox News debate---and many said it would hurt him. But the real estate mogul is continuing to maintain a narrow lead over Ted Cruz here.

Typically on the day of the caucuses, candidates race around the state speaking to as many voters as possible, as the capstone to a long retail campaign. But Trump has spent so few nights in Iowa that it was news when he recently stayed at a Holiday Inn here.

We know that he plans show up at several caucuses around the state Monday -- and even try to speak, though candidates aren't typically allowed to do that.

Who would put it past Trump to pull a stunt on the final day that nails down a win here in the Hawkeye state? We can only begin to guess what that might be.

Ground game tradition meets social media

There is no question that Ted Cruz has the most sophisticated ground game in Iowa on the GOP side this year.

But in the age of social media and in a race where one of the candidates has more than five million Twitter followers, will that matter?

Many previous winners from Jimmy Carter to Rick Santorum pulled off their victories after going county to county, sometimes talking to groups of voters as small as a dozen, and inspiring their volunteers to make sure those people turn out on caucus night. Ted Cruz has followed that traditional model, even visiting Iowa's 99 counties (again) in the final days before the contest.

His aides boast that they have some 1,530 precinct captains in the 1,681 precincts across Iowa, as well as 12,000 volunteers fanned out across the state. Some 1,000 additional volunteers have come in from out of state since Christmas. Some are so committed that they are living in dormitories by the Des Moines airport that are known as "Camp Cruz."

By 8 a.m. on Saturday morning, Camp Cruz was empty because those hard-core Cruz supporters had already fanned out for a day of calls and door-knocking to make sure voters know where to caucus.

Trump's ground game has been more of mystery, in part because his aides won't talk about it, tossing reporters out the door if they try to visit call centers in person. The other unknown factor is that many of Trump's supporters have never caucused before, so the campaign has a big task ahead in ensuring they turn out.

And we can't underestimate the power of Trump's social media footprint. Some first-time caucus goers who attended his rallies this week told CNN they had already clicked on the link Trump tweeted for the "caucus finder" on his website, where supporters can enter their address and zip code to find their caucus. And Trump has been pounding the importance of boosting turnout. In Clinton, Iowa, on Saturday night, he told his supporters that even if they were on their deathbed, he expected them to turn out.

The unexpected evangelical split

Evangelicals are often viewed as the most important voting bloc in Iowa in the GOP caucuses, helping boost conservative candidates Rick Santorum and Mike Huckabee to victory in 2012 and 2008, respectively.

But this year, they are split between Trump and Cruz, and to a lesser extent Ben Carson and Marco Rubio.

To everyone's surprise, many Christian conservatives have rallied around Trump despite his three marriages, marital infidelities and his dramatic evolution on the issue of abortion. Many told CNN in interviews that they admired Cruz's principled and consistent stands on abortion, gay marriage and religious liberty, but simply believe that Trump would make a stronger president.

To assuage doubts about his faith during his final push, Trump has been campaigning with evangelical leader Jerry Falwell Jr., who has served as a critical character witness for Trump by praising his private generosity and stating that Trump reminds him of his father, famed televangelist Jerry Falwell. Though he's had some embarrassing gaffes when talking about faith -- quoting "Two Corinthians" at Liberty University, for example, Trump played up his faith in the final weekend. He went to church on Sunday with his wife. On Saturday, he released a Facebook video showing the Bible that his mother gave him and promising evangelicals that he would never let them down.

Cruz's allies have continued to try to raise doubts about the authenticity of Trump's faith. On Sunday afternoon, Cruz urged evangelicals to choose the candidate who they knew they could count on. "This is your time to make the decision for the men and women of Iowa to say we can't get fooled again. The stakes are too high. We can't roll the dice."

The return of the Obama coalition (at least in part)

Bernie Sanders mounted a fierce challenge to Hillary Clinton by drawing on key pieces from the Obama coalition: particularly young voters. Their enthusiasm for Sanders is undisputable as he has drawn enormous crowds at college campuses here in Iowa and across the country and continues to engage with them on social media.

But he faces one hurdle that Obama didn't have in the 2008 Iowa caucuses: the intersection of geography and the complex rules of the Democratic Caucus. In 2008, the caucuses occurred much earlier in the year on Jan. 3. That meant many Iowa students supporting Obama were dispersed across the state in different precincts because they were still at home on winter break. This year, they are back on campus. That could hurt Sanders because it means they are more concentrated in certain precincts, giving less geographic breadth to his support than Obama's.

The reason that's important is because the Democratic winner in Iowa won't be determined by the overall number of votes. The winner is determined by the number of 'delegate equivalents' marshaled by their supporters in each precinct caucus. It's complicated, but if Sanders' young supporters are concentrated in a certain precincts, he may end up with less state delegate equivalents -- and that could spell a win for Clinton.

Des Moines Register pollster Ann Selzer raised this issue earlier this month when she noted that Sanders has maintained wide leads over Clinton in the three counties that house Iowa State University, the University of Iowa and the University of Northern Iowa. She told the Register that while those counties make up a sizable amount of Sanders' supporter, they only account for 21% of likely caucus participants. So even if Sanders pulls off a big turnout, that caucus quirk could be a strike against him here.

A loud New Yorker can impress polite midwesterners

Candidates who campaign here every four years love to talk about the state's reputation for "Iowa nice" -- the phrase that comes from the polite, friendly Midwest tradition of Iowa's farmers and voters.

But this year on the GOP side, those voters seem most taken by a candidate who is known for his bullying taunts of other candidates, reporters and whoever is the target of his Twitter feed that day.

On Sunday, Trump got increasingly personal in his descriptions of his chief rival: calling Cruz "a lying guy," "a hated guy" and "terrible."

The Iowa Nice tradition seems at odds with the latest Des Moines Register poll, which told us that Trump has among the highest unfavorable ratings of any of the candidates running -- and yet he is at the top of the pack.

Many Iowans say they are tired of "political correctness." This year, that sentiment may trump "Iowa Nice."

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