DES MOINES — In the end, it’s all about turnout.

With Hillary Clinton Hillary Diane Rodham ClintonHillicon Valley: FBI chief says Russia is trying to interfere in election to undermine Biden | Treasury Dept. sanctions Iranian government-backed hackers The Hill's Campaign Report: Arizona shifts towards Biden | Biden prepares for drive-in town hall | New Biden ad targets Latino voters FBI chief says Russia is trying to interfere in election to undermine Biden MORE maintaining a paper-thin lead in Iowa over her rival Bernie Sanders Bernie SandersMcConnell accuses Democrats of sowing division by 'downplaying progress' on election security The Hill's Campaign Report: Arizona shifts towards Biden | Biden prepares for drive-in town hall | New Biden ad targets Latino voters Why Democrats must confront extreme left wing incitement to violence MORE, the Democratic candidates are spending the final days before the Iowa caucuses trying to increase the number of their supporters who will participate across the state.

Polls suggest that a heavy turnout will benefit Sanders, who beats Clinton in polls among those who have never caucused before.

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If turnout is low, however, the edge goes to Clinton.

“If the turnout is not large, we’re going to be struggling,” the Vermont senator said at a Bloomberg Politics breakfast on Thursday.

He also acknowledged the difficulty in getting first-time voters to the caucuses, even if they are enthusiastic at rallies for his campaign.

“It’s easier to bring people out to town meetings and rallies than to necessarily get them to caucus,” he said.

A NBC News/Wall Street Journal/Marist poll out on Thursday shows that Clinton has a small edge over Sanders, 48 percent to 45 percent. The poll also reveals that, among past caucusgoers, the former secretary of State leads 52 percent to 40 percent.

Sanders, however, leads Clinton with those who have never caucused before, 56 percent to 41 percent.

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Tad Devine, a senior adviser for the Sanders campaign, said they feel confident in their organization with its 27 field offices around the state and 100 paid staff on the ground — augmented by other staffers who are working the caucuses even though they are not primarily based in Iowa.

The campaign also has 15,000 volunteers on the ground. By Monday, Sanders himself will have been in front of 58,000 people in the state, Devine said.

“When you think of all those people, all those events, you are already talking about a mass of people who can get you in a position to achieve victory,” Devine said in an interview with The Hill.

“We think we have identified enough voters to win the caucuses. But I’m sure if you talked to the Clinton campaign, they would say the same thing too,” he said.

Clinton allies with knowledge of the Democratic front-runner’s ground game in Iowa say they believe the results will be close but they think they’ll come out on top.

“I do think we’ll win, maybe by not much but we will,” said one Democratic strategist.

Some agree with that notion.

“I’m still not convinced that Sanders supporters are prepared to follow through with their pledge and engage in the caucus process,” said Jim Manley, a Democratic strategist who served as a spokesman for then-Senate Majority Leader Harry Reid (D-Nev.).

Still, Manley added that Sanders has managed to ride “a groundswell of anger” on some issues, just as Donald Trump and Sen. Ted Cruz (R-Texas) have done on the Republican side.

“From my years in the Senate, I knew he was awfully passionate about the issues but I for one am surprised that he’s doing as well as he is,” he said.

Steffen Schmidt, a professor of political science at Iowa State University, said he believes Sanders can convert campaign attendees to caucusgoers and that they will come out in droves.

“Why wouldn’t they?” he said. “They turned out for Barack Obama. And [Sanders] is getting bigger crowds than Obama.

“It’s real,” he continued. “You have the same feel as Obama rallies and I went to those.”

In Iowa, he said, a state that prides itself on voting from the heart, “young voters seem to be on fire and have the burn for Bernie … I think it’s going to be a large turnout.”

Both sides concede there are outside factors that could take a toll on turnout.

Weather is the biggest one. As of Friday the forecast in Iowa for Monday, the day of the caucuses, was mostly cloudy with a high of 39. But there’s a chance of a looming snowstorm the following day. If the snow comes early, turnout could suffer.

But, weather aside, Pat Rynard, the founder of the popular Democratic news site IowaStartingLine.com predicted Sanders would win. While he predicted that fewer caucusgoers would come out than in 2008, he said the number of participants will still be significant.

“I think he just barely pulls it out,” he said. “It’s going to be very close but I would rather have enthusiastic supporters than experienced supporters and a large operation for caucus night.”