MUSCATINE, IOWA – Look no further than Pearl City Station, a plain brick building set along the banks of the Mississippi River, to understand the growing sense of uncertainty seeping into the Democratic Party’s 2020 primary contest.

Inside, 200 Iowa Democrats recently sized up Joe Biden, the former vice president and one of their party’s leading presidential candidates. He engenders respect and admiration but generates little excitement.

One elderly man sitting in the back of the room fell asleep as the former vice president shared his vision for America’s future in unusually hushed tones for nearly 45 minutes without taking questions.

Afterward, David Metz, a member of the county Democratic committee, said that despite a campaign season that has already featured millions of dollars spent, countless miles logged and four debates staged, there is a deepening feeling of indecision among local voters who now have less than 100 days to finalize their 2020 pick.

“Nobody knows what to do,” Metz said. “They’re all afraid. There’s a lot of anxiety.”

In almost every campaign cycle, there comes a phase of indifference, fear and difficult questions. But in the 2020 cycle, Democratic officials hoped that the fervent desire to beat Trump would eventually lead to an enthusiastic embrace of its presidential field.

The lack of enthusiasm for Biden’s candidacy underscores a broader trend emerging in the states that matter most in the Democratic Party’s high-stakes presidential nomination fight: Primary voters appear to be getting less certain of their choice as Election Day approaches.

The historically large field, while in part of measure of the desire to oust the incumbent president, has also made it harder for the top contenders to forge a more focused contest. Nine Democrats so far have qualified for the party’s November debate and a dozen more are still fighting for attention. Among the top tier, the liabilities of Biden, Sen. Elizabeth Warren and Sen. Bernie Sanders, in particular, are becoming more visible as Iowa’s Feb. 3 caucuses approach.

Major donors and party leaders across the country have publicly and privately raised concerns about the direction of the primary election recently as well. But interviews with dozens of primary voters across Iowa and New Hampshire in recent days reveal a pervasive feeling of unease.

Polling suggests that the number of undecided voters in Iowa has jumped significantly in recent weeks. And even among those who have a favorite candidate, most say they could change their mind before voting begins.

Tom Steyer, a billionaire progressive activist, is among those lower-tier candidates aggressively fighting to capitalize on the uncertainty. He’s vowed to spend at least $100 million of his own money in the campaign, although he acknowledged in a weekend interview that his investment could shift up or down depending on conditions on the ground.

“We’re three months out from Iowa and we thought that there would be a lot of indecision, but it’s definitely higher than we would have expected. No question,” Steyer said. “That is something that has to be true if I’m going to win. And it is true.”

Just ask the voters.

In New Hampshire, Greg Bruss, a 68-year-old retired teacher, says he’s usually volunteering for a candidate by this time in the primary cycle. That’s not the case this year as he mulls voting for either Sanders or Warren.

“The times are that much more dire,” Bruss said. “I don’t want to get it wrong.”

Former New Hampshire state Sen. Bette Lasky says she’s impressed with the Democratic field, but she’s remained on the sidelines as well, even after hosting house parties for several candidates.

“Generally, I don’t have trouble making up my mind,” she said. “But (it’s) difficult for me to get out there behind any one candidate.”

Back in Iowa, 43-year-old Waterloo school employee Danielle Borglum said she expected to finalize her decision after watching the last debate, but she couldn’t do it.

“I didn’t realize the amount of people that we had as candidates!” Borglum said. “So many people have a plan. Is anyone really right?”

Bev Alderson, a 59-year-old retired teacher from Mt. Pleasant, Iowa, said that she has “a couple of frontrunners, but they’re not etched in stone.”

“There’s too much to be said yet. There’s too many things that are happening and going on, it’s just too early,” she said.

While significant, history suggests that the uncertainty currently defining the 2020 primary season is not totally unique.

Before Iowa’s 2004 contest, for example, former House Majority Leader Richard Gephardt, Connecticut Sen. Joe Lieberman and Vermont Gov. Howard Dean all led the polls at times before then-Massachusetts Sen. John Kerry made a late surge to win.

And three months before Iowa’s 2008 Democratic caucuses, most polls had Hillary Clinton with a significant lead over John Edwards and a little-known Illinois senator named Barack Obama. Obama, of course, went on to win the Iowa caucuses by almost 8 points and Clinton finished third.

That history, backed by polling that shows most voters could still change their minds, is convincing low-polling underdog candidates to keep fighting.

“One of the things I’ve learned by listening to the people of Iowa is they tend to make up their minds fairly close to caucus night,” former Texas Rep. Beto O’Rourke told reporters during a forum in Des Moines last week.

New Jersey Sen. Cory Booker, who hasn’t topped 3% in any Iowa poll since April, said he was encouraged by a crowd of 200 that showed up to see him speak the night before. He said he’s getting a clear message from voters who say, ”‘I’m excited about you — you’re first on my list, or you’ve moved up from four to two,’ which I’m learning is really important in the Iowa caucuses.”

And former Housing Secretary Julian Castro warned supporters last week that he’d need to raise $800,000 by the end of the month to keep his campaign alive. But he, too, seized on the large number of undecideds.

The primary campaign, Castro said, is “more unstable than it’s ever been.”

“You have a lot of people in these polls that, even though they express a preference for one candidate or another, are saying that they can still change their mind,” he said. He added: “Three months is probably 10 lifetimes in politics.”

Jennifer Konfrst, a first-term Iowa state senator, agrees.

She’s supporting Booker, but she says many of her friends have already changed their minds about which candidate they like best.

“So many of my friends have three top choices — and they’re not the same three,” she said. “Anybody who says they know what’s going to happen is lying.”