That has made Nevada, often called the wild west of the early state contests, even more of a Silver State scramble this year -- looming as one of the biggest mysteries on the presidential nominating calendar.
Unlike Iowa, New Hampshire and South Carolina, there is no reliable polling here, in part because so few people could show up. The campaigns do not have a reliable list of caucus-goers from 2008 and 2012, because the state party did not maintain that data in a fashion that they could use. And unlike Iowa -- which has long been the first-in-the-nation caucus -- very few Republican voters here are familiar with the basic drill of what a caucus entails.
The bottom line? No one has any idea how many voters will turn out in Nevada on February 20, and that makes it anyone's game to win.
In that sense, Nevada offers a key test next year of whether an untraditional candidate like Trump can muster the kind of organizational strength that more establishment campaigns like Bush and Rubio are bringing to bear.
'This is a movement'
"This is a movement," Trump told an enthusiastic crowd inside the Mystere Theater at the Treasure Island casino on the Las Vegas Strip Thursday. "This is a movement to take our country back."
But any longtime political hand in Nevada will say that it will take a lot more than a movement to win in the Silver State. And that is the emerging test here for Trump's team here: whether they can channel the energy for his candidacy into a reliable turnout organization of volunteers.
"It's happening; I'm on Team Trump," said A.J. Maimborg, who previously caucused for Ron Paul and is now volunteering to train caucus-goers for Trump. "We're having a lot more meetings now; we're getting together to get the organization done, and we get more supporters every day."
Maimborg, who was at the Trump rally wearing a black "Trump 2016. Build the Wall" T-shirt, said she ruled out Rand Paul -- once thought to be a serious contender here -- because "he's not his father" and "he flip-flops too much."
She ruled out Bush, because "we don't need another Bush," and ruled out Rubio because she didn't like what she read about him and doesn't think he's up for the job.
"I was a Republican for years and I got tired of both parties, so I went to the American Independent Party. Donald Trump brought me back as a Republican," said Maimborg, adding that she likes him "because he can't be bought."
That energy for Trump -- and for Ben Carson, who was most often named by voters as their second choice at Trump's rally here Thursday -- has raised the stakes in Nevada for Rubio and Bush, who both hoped Nevada would serve as a firewall that could create momentum for their candidacies before they faced off in their home state of Florida.
After less than 33,000 of the state's 400,000 GOP voters showed up to caucus in 2012, allies of Bush had hoped the state's leaders would agree to switch from a caucus to a primary to ensure greater participation. But the legislature adjourned without taking that step earlier this year. So Bush's team, headed by Nevada-based strategist Ryan Erwin, who led Mitt Romney's successful efforts here in 2008 and 2012, is engaged in a labor intensive effort to train potential caucus goers nearly every other day.
The hope through those trainings, he said, is to "remove the fear of the unknown" in the caucus process.
"We are well organized. We understand what it takes to win, and we are keeping our head down and focused on the task at hand," Erwin said. "A caucus is, by its nature, is a clunky process and difficult to understand -- it's not what people are used to doing," said Erwin, noting that Nevada voters are used to the ease of being able to cast ballots early at their grocery store.
He noted that Nevada also has a disproportionately high number of people that work off-hour shifts: "It's a different commitment than a primary or a general election vote and it takes longer."
Courting party leaders
To help round up and organize those core Republican voters, both Bush's team and Rubio's have worked assiduously to notch endorsements of party leaders here.
Bush won the support of Nevada U.S. Sen. Dean Heller, and has played up his potential to do well among the sizable population of Hispanic voters here in the general election, because of his more welcoming tone on immigration. (Though Nevada is often referred to as the first Latino primary, there is little evidence to suggest that many Hispanic voters will turn out to caucus for Republicans in February.)
Rubio, who began a three-day swing here Thursday night in Summerlin, has played up his Nevada roots after spending time here as a youth. He has also made strong entreaties to the Mormon community here, which helped deliver the state twice to Romney. The Florida senator also recently landed the support of Scott Walker's Nevada campaign chairman, former Nevada Gov. Bob List.
Lt. Gov. Mark Hutchison, Rubio's campaign chairman in the state, pointed to that pickup as another good sign for the Florida Senator as he rises in national polls.
"We're really seeing a lot of momentum here in Nevada for Senator Rubio," Hutchison said. "People just see him as a next-generation leader. ... One thing that you're seeing is that a lot of people who saw Governor Walker as attractive are now are moving their allegiance and their resources over to our effort."
While Paul was viewed as a strong contender earlier this year, because it was assumed that he would inherit the organization of his father, Ron Paul -- the elder Paul's support has splintered among the many candidates in the GOP field.
One of the beneficiaries of that splintering has been Carson, who has not campaigned as much here as Bush and Rubio, but is, by all accounts, building a strong ground organization.
Jimmy Stracner, the former state director for the Republican National Committee, shrugged off the endorsement battle between Bush and Rubio for the top names: "It's not surprising that the political class has gone with Rubio and Bush," he said.
"This is not a race for endorsements. Dr. Carson is not part of the political class," Stracner said. "He's said from day one he's not going to lick the boots of billionaires... People are truly inspired by him, meaning we have the ability to pull in people who have never caucused before."
With so much interest in the race, the caucus experience may be a first-time experiment for many Republicans in Nevada, and the state may ultimately be won not with momentum, but by the campaign who shows the kind of relentless follow-through needed to turn them out.