Cole Johnson, a 19-year-old college student in south-central Wisconsin, had never voted in a governor’s race before. But the prospect excited him so much that he arrived at a candidate forum one evening last week to see his preferred would-be governor, Francesca Hong, a democratic socialist and state lawmaker, take the stage.

“I’m a Honghead,” Mr. Johnson said, adding that he hoped her candidacy would propel “disillusioned” voters to the polls.

Ms. Hong’s campaign has energized voters across the state, raising hopes among her supporters that her working-class origins, blunt talk and progressive ideology can translate into a new approach for Democrats to lead Wisconsin after the exit of Gov. Tony Evers, a fellow Democrat who chose not to run again.

Others in the crowd at the candidate forum were there to survey the candidates, while commiserating with their fellow Democrats over a wild couple of weeks in state politics — and a noisy primary that has generated both enthusiasm and angst.

The race for governor is crowded, with five candidates vying for the Democratic nomination. With less than three weeks to go before Election Day, the field is still in flux: An establishment front-runner left the race this month after discovering campaign finance problems, and another candidate dropped out only to jump back in to receive a late endorsement from Mr. Evers.

Then there is Ms. Hong, who has hurtled to the front of the Democratic pack in polls with a platform that includes increasing the minimum wage to $20 an hour, allowing local governments to raise income taxes on high earners and putting a freeze on the construction of new data centers.

“There’s probably nobody too progressive for me,” said one Democrat, Amy Stowe of Merrimac, Wis. “But what if we go too progressive and the Republican wins?”

Their state has suddenly emerged as a national testing ground for the party, as democratic socialists have risen to power in New York, Seattle and other cities around the country. But whether a socialist can succeed in winning a general election in a Midwestern swing state with a habit of electing centrists is a matter of anguished debate among Wisconsin Democrats.

The closely watched Marquette University Law School poll released last week pointed to a still evolving Democratic race, with 45 percent of voters saying they are undecided. The poll, conducted from July 8 to 16, showed Ms. Hong leading the field with 26 percent of the vote, and Mandela Barnes, the former lieutenant governor, with 15 percent.

Many Wisconsin voters said they felt whipsawed by the drama in the primary, now even less sure of who to support than they were weeks ago. At the candidate forum in Sauk County, Democrats said they were nervous that it remained unclear which candidate had the best chance of defeating a Republican.

Voters are “kind of gobsmacked,” said Karen DeSanto, a Democratic state representative. “They’re asking, what is the strategy?”

The stakes for Democrats in Wisconsin are nerve-wrackingly high. More than a decade after Republicans won control of the state government, Democrats have fought to take it back, and under Mr. Evers, the party has made slow but steady gains. Liberals have won a solid majority on the Wisconsin Supreme Court, led the creation of new state legislative maps that undid a Republican gerrymander and, for the first time in years, are seen as positioned to win control of the State Senate and possibly even the Assembly.

“They could get a true governing trifecta,” said Joe Zepecki, a Democratic strategist. “The pressure that the left is feeling is part of why you are seeing this disarray in the last couple of weeks. People are very afraid of missing the opportunity ahead.”

Keeping a Democrat in the governor’s office for another term was not expected to be such a steep hill to climb.

But as Democratic voters survey the field, some worry that Ms. Hong may be too far to the left; that Mr. Barnes may not be popular enough, having already failed in a bid for U.S. senator in 2022; and that three other candidates, Kelda Roys, Joel Brennan and David Crowley, are just too unknown to most voters. Republicans are expected to nominate Representative Tom Tiffany, who grew up on a dairy farm and worked as a dam tender before going into politics.

“There’s two issues: One, who would make the best governor as a Democrat? And the other is, which of them is capable of defeating Tiffany in November?” said Paul Soglin, a longtime Democrat and former mayor of Madison. “I have absolutely no clue who’s capable of doing that.”

Ms. Hong and Mr. Tiffany have already clashed over their responses to the fatal police shooting of a man in Madison last week. Ms. Hong joined protesters with a bullhorn and denounced the killing, saying, “This state-sanctioned violence was an execution.” Mr. Tiffany said her opponent was inflaming division and rushing to judgment before the facts were fully known.

Some voters have questioned Mr. Evers’s involvement in the campaign, as he first declined to support any one candidate and then gave a surprise endorsement to Mr. Crowley, an establishment candidate who left the race briefly, then returned. After the endorsement, Mr. Evers departed on a trade mission to Africa.

“It makes me uneasy,” said Priscilla Keach, 57, who works in sales and attended the candidate forum in Sauk County. “Why is the governor endorsing someone who just dropped out?”

Even a former Democratic governor of Wisconsin, Jim Doyle, said in an interview that he had been impressed by the strength of Ms. Hong’s campaign and believed that she could win in November.

“I was a pretty centrist candidate, and I think that that generally is how you win in Wisconsin,” he said. “But that may be old-time thinking.”

Ms. Hong’s opponents have eyed her ground game nervously. A Madison resident who also works as a chef, Ms. Hong has amassed an army of some 7,000 volunteers statewide, including members of the Democratic Socialists of America.

Allison Geyer, a campaign spokeswoman, said that of the core team of a half-dozen workers in the Hong office on a day-to-day basis, one or two are D.S.A. members who are volunteering their time.

“Their role is very much the operational ground game,” she said. “They’ve been boosting our canvasses on their socials. They’ve been knocking on doors. They’ve been building their organization since the Bernie era, so there’s a lot of bodies, and people are excited.”

Across the state, Democratic county chairs said that they are hoping that the eventual nominee will have a compelling pitch to voters based on affordability and what they see as the damage inflicted by the Trump administration. Voters are worried about gas prices, housing costs and an unsteady job market — and looking to the next governor to find solutions, Democrats said.

“People are making a choice between health care and putting gas in their cars,” said Brenda Vinall-Mogel, the chair of the Burnett County Democrats.

As Jim Walker, 71, waited for the candidates to begin speaking, he said he had already made his choice: Ms. Hong. Mr. Walker used to vote for Republicans, but about 20 years ago, he turned away from them, he said, voting for third-party candidates and Democrats instead.

“I’m ready for a democratic socialist as governor,” he said. “She understands working people and their struggles.”

After the forum ended, however, Mr. Walker walked outside with a disappointed look on his face.

“I was all in for Fran, but I felt she didn’t have very substantive answers to some questions,” he said. “Now I don’t know.”

Ruth Igielnik contributed reporting.