One week from Monday, the most enthusiastic Iowa voters will head to their churches and school gymnasiums for the time-honored tradition of the caucus - the night they pick how delegates will be awarded to the presidential candidates.
For Hillary Clinton, it threatens to be a repeat of her 2008 nightmare: a once long-shot candidate rides a groundswell of enthusiasm from first-time caucus goers and young people and defeats her. Then, it was Sen. Barack Obama. But this time, could it be Sen. Bernie Sanders?
That's certainly the outcome Sanders is predicting. He campaigned at Upper Iowa University in Fayette on Sunday.
"When you reach the end of a campaign, people say a whole lot of things. And one of the things that they did is make a lot of attacks. And I have been attacked time and time and time again, but I think for many Iowans, it kind of sounds familiar. 'Bernie Sanders doesn't have experience. Bernie Sanders is naive. Bernie Sanders' ideals are pie in the sky,'" he told the 400 people who came to his town hall. "We heard that back in 2008. Iowans did not fall for it then. I don't think they're going to fall for it this campaign."
For now, political scientists and Democratic strategists across the state still give Clinton a slight edge. The latest CBS News Battleground Tracker poll had Sanders leading Clinton 47 percent to 46 percent, within the margin of error. But the caucuses come down to more than who is the most popular in the polls.
"Clinton learned from her mistakes from eight years ago," Timothy Hagle, a political science professor at the University of Iowa, told CBS News. "She's got a very good ground game but Sanders does too. Clinton may have more staffers, but at a particular point it doesn't matter if you've got an extra 30 staffers:...it's more the structure and whether they're doing what needs to be done and identifying supporters all the way down to the precinct level."
The supporters who show up to caucus at Iowa's 1,681 precincts Monday will determine how the state's 1,406 delegates are awarded.
Democrats who still say Clinton has a good shot at winning point to the fact that her support is widespread across the state, and her team has been working for months to train volunteers on how to win individual precincts.
"Her team's been on the ground a lot longer, has been organizing here for a while, and some of the biggest and best names in Iowa politics are involved with it," said Grant Woodard, a Des Moines attorney who has worked on statewide and national Democratic campaigns. He worked for Clinton's team in 2008 but is unaffiliated this time around.
Norm Sterzenbach, the former executive director of the Iowa Democratic Party, told CBS News that the two campaigns have about the same level of organizational activity, such as staff, surrogates, candidate rallies and volunteer recruitment.
"The difference between the two is that Clinton has had a large operation for a lot longer and they have laid the groundwork earlier, and I think that gives her a significant edge," said Sterzenbach, who is not working for either candidate. "She's had a statewide organization, not just in big areas that have been identifying supporters, recruiting precinct captains, training precinct captains about what to do in the lead up to the caucuses."
"Sanders was quite late to the game on that," he said.
He also noted that while Sanders stands to bring in new caucus-goers, Clinton's supporters tend to have more experience with caucuses, which means her campaign doesn't have to spend as much time teaching people what to do or getting them comfortable with the process.
It's hard to get an apples-to-apples comparison of what each side is doing. Rania Beatrice, one of Sanders' Iowa-based spokespeople, told CBS News last week that more than 15,000 volunteers have completed at least one campaign shift in Iowa. The Clinton campaign said hundreds of volunteers canvass for their candidates each weekend, and said last week that 80 percent of people who had signed up to volunteer in the previous two weekends did so even in inclement weather. They also have 26 offices across the state.
Geography is another critical factor in the race. Sanders has proven a hot commodity on college campuses, and the latest Des Moines Register poll found his support dwarfs Clinton's, 52 percent to 30 percent, in three counties: Black Hawk, where the University of Northern Iowa is located; Johnson, home to the University of Iowa; and Story, where Iowa State University is located.
The poll director, J. Ann Selzer, said those counties are responsible for 27 percent of his supporters in the state, but they are home to just 21 percent of all the people who are likely to participate in the Democratic caucus.
The problem for Sanders is that he can only get a small number of delegates from each the college campuses whether he wins the precincts by hundreds of supporters or just a few dozen.
"If they dominate some college precincts," Hagle said. "It's not going to be helpful to them."
When then-candidate Obama won the caucus in 2008, his college supporters were home on winter break and therefore more spread out across the state. And the campaign was able to bus in students who grew up in neighboring states so they could register in their college precincts and hold down support there.
With the 2016 caucus a month later, students will be back on campus for the caucuses, meaning they'll flood the college precincts. The Sanders campaign is making an effort to combat that concentration with a "Go Home for Bernie" campaign to ferry students back to their hometowns in Iowa to caucus, according to the New York Times. It's unclear whether that will be an effective way to combat the supporters Clinton has lined up across the state, especially if students need to be back on campus Tuesday for classes or exams.
For Sanders, "It could easily be death by 1,000 cuts," Sterzenbach said. "[Clinton] could just be picking up delegates left and right across the state and part of that comes back to having the organization early and on the ground."
The advantage to the younger supporters is that they have energy.
"I support everything that he stands by and I'm really passionate about getting other people motivated about voting like I am, and getting them to vote for Bernie and support him," 18-year-old Ty Lane, of Bettendorf, Iowa, told CBS News as he knocked on doors for Sanders in Davenport.
Clinton has her dedicated supporters, too. Forty-year-old Carissa Alvarez of Coralville, Iowa will not only be attending her first caucus to support Clinton next week, she's also signed up as a "caucus volunteer" who will help round people up on caucus night.
"I'm a huge Hillary supporter," she told CBS News. "I think this year's important. I think it's kind of like a turning point and we need to get involved so we get the right person in there. I think if we get the wrong person, it's not going to go well."
Other factors could tilt support one way or the other, but experts say they matter less than the ground game of each campaign.
One is endorsements: The Des Moines Register picked Clinton for its endorsement in the Democratic nomination. But the newspaper's track record is weak: since 2000, it has endorsed an eventual caucus loser five out of six times on both the Republican and Democratic side. In 2004, the paper endorsed then-Sen. John Edwards. Then-Sen. John Kerry went on to win the caucus and Democratic nomination. It endorsed Clinton in 2008 - and that didn't help her beat Obama.
Endorsements haven't mattered much in the recent past.
"They're basically a feather on the scale, but in a tight race, feathers matter," Goldford said.
Then there's the question of what will happen to the supporters of the third Democratic candidate, former Maryland Gov. Martin O'Malley, in the precincts where he doesn't have enough support. If a candidate receives fewer than 15 percent of people who show up to a caucus site, that candidate is deemed to be not viable and those supporters must go home or join other campaigns.
If Sanders does show strength across the state and is running close to even in many precincts, O'Malley's supporters could help tip the balance toward one of the candidates. O'Malley received just 5 percent support from likely Democratic caucus-goers in CBS' Battleground Tracker.
CBS News Senior Political Editor Steve Chaggaris and Digital Political Reporter Hannah Fraser-Chanpong contributed to this story.