Wisconsin Lieutenant Governor Mandela Barnes, who has opened a narrow lead in polls of the crowded contest for the state’s Democratic US Senate nomination, got a significant boost last week when US Senator Bernie Sanders announced his endorsement. Barnes got another boost over the weekend when US Senator Elizabeth Warren flew into the state to campaign with the 35-year-old contender at rallies in Milwaukee and Madison. But what may turn out to be the biggest boost came Monday morning, when another contender who had drawn considerable progressive support quit the race and endorsed the lieutenant governor in the August 9 primary.

“We ran out of money,” said Outagamie County Executive Tom Nelson, who had mounted a Senate bid as an enthusiastic proponent of Medicare for All, a Green New Deal, and immigrant rights. “You got our campaign this far,” Nelson told supporters in an early morning message, “let’s get [Barnes] across the finish line and beat [Republican incumbent] Ron Johnson.”

Nelson, who built a small but ardent base of young labor-aligned progressives and climate activists, identified Barnes, a fellow progressive, as “the one candidate who is not trying to buy this election.”

He later explained:

I am proud of the race we ran and the ideas we put forward like a national industrial strategy to build good paying jobs in our communities, Medicare for All to ensure everyone has access to health care, a one-of-a-kind food sovereignty plan to lift up our family farmers, bust up Big Ag and help consumers, and a Green New Deal so our children and their children have a planet to live on.

Unfortunately, money matters way too much in politics and running against two self-funding millionaires proved too much for this pastor’s kid.

That was a reference to two other serious contenders for the nomination, Milwaukee Bucks executive Alex Lasry, whose largely self-funded campaign has, according to Open Secrets, spent almost $15 million on an intensive media campaign that has made him the second-place runner in most polls, and state Treasurer Sarah Godlewski, whose campaign has spent almost $6.2 million. Barnes has relied on more than 130,000 individual contributions averaging $35 to $40 to fund a campaign that has so far spent around $4.7 million; while Nelson, who has relied on small donations as well, has spent roughly $1.4 million, according to the latest Open Secrets review of the contest.

When I spoke to Nelson on Monday morning, he said he was proud of running a race that had won the endorsements of former Democratic governor Tony Earl; state Senator Kelda Helen Roys, a leading pro-choice advocate; a number of union locals; and the Wisconsin affiliates of groups such as Our Wisconsin Revolution and the Sunrise Movement. But he was realistic. Nelson recognized that he’d been running fourth in recent polls, with 7 percent support in a late June Marquette Law School survey. The same poll put Barnes in the lead in the Democratic primary, with 25 percent, while Lasry was close behind with 21 percent. Godlewski was at 9 percent, but there was a widespread sense that she was gaining traction because of her ardent advocacy for abortion rights following the US Supreme Court’s decision to allow states to gut reproductive rights protections. Several additional candidates were at or under 1 percent.

When I talked with Nelson about his endorsement of Barnes, the county executive from an industrial region of the state’s Fox River Valley focused much of the conversation on the fact that the lieutenant governor has deep roots in Wisconsin and a working-class background. Barnes, a former community organizer, is the son of a factory worker, who was active with the United Auto Workers union, and a Milwaukee teachers union member; his grandfather was active in an independent steelworkers union in the days when Milwaukee was one of the busiest factory towns in the United States.

Nelson and Barnes, both former legislators, have progressive records on issues of economic, social, and racial justice. And they’ve been regulars on union picket lines and at rallies over the years. When Senator Sanders rallied in Racine, Wis., in June with striking United Auto Workers union members, Nelson and Barnes each arrived early and stayed late for the event. It was no secret that both candidates wanted an endorsement from Sanders, a frequent visitor to the state who carried 71 of Wisconsin’s 72 counties when he sought the Democratic presidential nomination in 2016. Last Monday, the senator joined Warren and Senator Cory Booker (D-N.J.), as a Barnes backer. His statement of support for Barnes read:

As the son of a public school teacher and UAW assembly line worker, Mandela Barnes knows the struggles of the working class. His agenda advances the interests of working families, not the billionaire class. I’m proud to endorse Mandela because he is the best positioned progressive candidate who will win both the primary and defeat Ron Johnson in November.

Now, Nelson has added his endorsement to the growing list of Barnes supporters. Barnes responded by saying, “I deeply respect Tom Nelson’s commitment to the working people in this state and am thankful to have his endorsement.” Then, directing a Twitter message to his former rival, Barnes added, “Together, @NelsonforWI, we’re going to send Ron packing!

For his part, Nelson said he thinks that his supporters will help move Barnes “out of the margin of error and into a solid lead.”

“Unlike billionaire son-in-law Ron Johnson and some of the other Democratic candidates, Mandela Barnes knows firsthand what it’s like for families struggling with inflation, without health insurance or a lack of gainful work,” said Nelson. “He has a strong progressive record and is well positioned to finish Ron Johnson off.”