The scene is set, and at this moment, on the day of the Iowa caucus, the answer to the question "Who will win?" is no clearer now than it has been over the past year.
The Republicans are likely to see Donald Trump or Ted Cruz as their first victor, while Hillary Clinton and Bernie Sanders are neck-and-neck as their supporters gather at caucus sites tonight.
And boy, has the landscape changed in a year. On Feb. 1 last year, the likely front-runner and 2012 nominee, Mitt Romney, had just announced he'd step aside for a politician of the new generation. The Des Moines Register (DMR)/Bloomberg Iowa Poll was showing Scott Walker, Rand Paul, Mike Huckabee and Ben Carson leading the pack (Trump had 1 percent support, Cruz 6 percent and Marco Rubio 4 percent).
On the Democratic side, Clinton's domination of the race was a foregone conclusion in Iowa. In that same poll, she registered 56 percent support, while Sanders foundered at 5 percent. The idea of a socialist winning any early contest seemed faintly outlandish at the time.
While it's always the case that the earliest polls taken a year out from the race have little bearing on the contest, it is still a little startling to see how the race has turned utterly upside down. The poll out this weekend by DMR/Bloomberg shows Trump leading Cruz 28-23 percent with Rubio at 15, while Walker ended up walking away from the race before it officially began. Clinton and Sanders are neck-and-neck, with Clinton holding a slight 45-42 edge.
The candidates are still scurrying around the state looking for last-minute support -- the 10 Republican candidates currently in Iowa held 16 events Sunday prior to the caucuses, after holding a combined 68 events over the weekend. Clinton brought out her husband, former President Bill Clinton, and her daughter Chelsea to drum up enthusiasm in an effort to counter Sanders' huge crowds around the state.
Only John Kasich is eschewing the state entirely. He's in New Hampshire Monday for three events, and Jeb Bush is splitting his time, with one Iowa midday event before he sprints out to New Hampshire, where he's vying against Bush, Chris Christie and Rubio for the establishment nod.
We say it every four years -- and it's still true -- that turnout will make the difference. Broadly speaking, it's evident that huge turnout will work in the favor of Trump and Sanders, who are relying heavily on new voters to caucus. Low turnout suggests that the well-organized traditional caucus-goers of Cruz and Clinton could prevail.
For Trump, all eyes are on whether his support is simply made up of Trump fans or actual caucus-goers. "One thing everyone agrees on: his crowds are the biggest of any non-incumbent Republican caucus campaign in history, and many haven't caucused before," Iowa Republican strategist Tim Albrecht points out. "Will they show up?"
"I don't have to win it," Trump told "Face the Nation" moderator John Dickerson. "But I think it would be really good to win Iowa. I'd like to win Iowa....I think we have a good chance of winning Iowa."
Cruz, meantime, is banking on a deeply-researched data targeting program, a large campaign organization, and what he calls "the old Reagan coalition coming together" to boost him to victory.
"We're seeing conservatives and evangelicals and libertarians and Reagan Democrats. And if conservatives come out, we're going to win tomorrow," Cruz said on "Fox News Sunday."
It's a similar situation on the Democratic side, as political observers shared specific benchmarks that would bode well for Sanders. "If the turnout crosses the 160-170,000 mark what that means is Bernie expanded the electorate and that makes a difference," said former Iowa Democratic Party chairman Scott Brennan.
Jerry Crawford, Hillary Clinton's Midwest co-chairman, is looking at the big counties.
"The first thing to watch for is what is happening in Iowa's 3 biggest counties: Polk, Linn and Scott --[in other words]...Des Moines, Cedar Rapids and Davenport," he said.
Clinton lost all three of those counties by double digits in 2008, and Crawford suggested Sanders would have to beat her there soundly to overcome her "more uniform strength statewide."
CBS News Digital Journalist Kylie Atwood contributed to this report.