After a year of campaigning and a blizzard of negative ads, Iowa voters will finally decide Monday whether to back the anti-establishment candidates who have made this wild presidential election so unpredictable or stick with more mainstream contenders.

The outcome will answer whether the surge of enthusiasm that has rocketed insurgent candidates to the top of the Iowa polls can translate into votes in a low-turnout caucus that thrives on the nitty-gritty minutiae of getting Iowans to the caucus.

Billionaire Donald Trump, who has largely abandoned the retail politics long key to the caucuses, is in a two-way race with Texas U.S. Sen. Ted Cruz for the lead. Florida U.S. Sen. Marco Rubio, trying to consolidate the mainstream GOP base, hopes the results will stamp him as the establishment favorite.

The Democratic side offers a different source of intrigue. Former Secretary of State Hillary Clinton, long the front-runner and favored pick of the party elite, is trying to stave off a surprisingly effective challenge from Vermont U.S. Sen. Bernie Sanders and a blend of economic populism igniting the liberal base.

A defeat here would surely tarnish the aura of inevitability her campaign has painstakingly built as she heads into another tough contest next week against the senator in his next-door neighbor of New Hampshire.

A Des Moines Register-Bloomberg Politics poll unveiled late Saturday shows just how tight the race has grown. Trump led the Republican field with 25 percent, Cruz was at 23 percent and Rubio trailed at 15 percent. Clinton and Sanders, meanwhile, were in a statistical dead heat.

Analysts expect a record voter turnout thanks to mild weather — a blizzard barreling in on the state isn’t likely to hit until early Tuesday — which could further fuel the campaigns of Trump and Sanders. Both contenders are relying heavily on first-time voters otherwise unlikely to gather at 7 p.m. Monday to caucus.

Trump and Cruz

The battle for Iowa voters has increasingly turned into a race to the flanks of both parties, with Sanders and Trump capturing the hearts of many frustrated voters with a mix of populist zeal and insurgent appeal.

“He brings everything to the front. How do I explain this? He brings the issues to the table, and he’s forcing the other candidates to address them,” said Shannon Barton, a Trump supporter at a rally in Council Bluffs who plans to caucus Monday for the first time.

“I guess we’re tired of the crap,” Barton said. “There’s so much political nonsense. And Trump’s an action taker.”

A victory for Trump would be disastrous for Cruz, an ideological purist and tea party favorite who has built-in advantages with Iowa’s overwhelmingly conservative and evangelical Republican electorate. He’s focused his campaign in recent weeks on rural voters as he finishes a 99-county tour of the state.

Once atop the polls, though, he’s been hurt by an uneven performance at Thursday’s debate in Des Moines, criticism from the state’s six-term governor over his opposition to subsidies for ethanol and heightened attacks from his more mainstream rivals.

Among them is Rubio, who is inching up in the polls and showing new traction with some voters as the establishment favorite over former Florida Gov. Jeb Bush, Ohio Gov. John Kasich and New Jersey Gov. Chris Christie.

“Just listen to him talk. Listen to where he came from,” Janice Stavnes said after hearing Rubio speak in Ames. “Cruz seems a little arrogant. Rubio, I just adore. He’s a little young. But Kennedy was young, too.”

Clinton and Sanders

Clinton has staged big rallies across Iowa, bringing her husband, former President Bill Clinton, with her to try to counter Sanders’ rallies. The two candidates have headlined rival events in the same Iowa towns over the past three evenings, including dueling speeches at Des Moines events late Sunday.

Faced with a potential repeat of 2008, when her loss to Barack Obama helped catapult him to leads across the South, Clinton tells crowds that she’s learned to be a better candidate from that campaign defeat. Her husband, too, has been unleashed in Iowa as her fiercest advocate.

“There are certain, almost intangible qualities that determine whether a president succeeds or not,” the former president said at a weekend rally. “You need a sticker. A sticker: Someone who won’t quit on you. She’s the best at that I’ve ever known.”

Sanders, meanwhile, has focused on targeting the same sort of young voter who helped power Obama to a surprising victory over Clinton at the 2008 caucus. He told dozens of supporters at a garage in rural Charles City that his strategy depended on a surge in turnout.

“In my view, we will win on Monday night if — here’s the big if — if there’s a large voter turnout,” he said. “If we can get working-class people who do not always go to caucus … if we can get young people to get involved in the political process, we will win.”