Progressive champion Mandela Barnes emerges as Dem to take on Ron Johnson in Wisconsin
(Wisconsin Department of Military Affairs photo by Vaughn R. Larson)

The Democratic primary field in the race to unseat Republican U.S. Sen. Ron Johnson of Wisconsin shrank for a second time in less than a week on Wednesday as Milwaukee Bucks executive Alex Lasry announced he would end his campaign, leaving progressive Lt. Gov. Mandela Barnes as the frontrunner.

Barnes received key endorsements from Sens. Bernie Sanders (I-Vt.) and Elizabeth Warren (D-Mass.) in recent days, and on Monday fellow progressive candidate Tom Nelson said he was throwing his support behind the lieutenant governor after his campaign ran out of money.

Lasry said he was also endorsing Barnes ahead of the August 9 primary, telling Politico that "the most important thing that we can do for Wisconsin is to get rid of Ron Johnson."

"I firmly believe that if there was no path to victory, the best thing to do is to make sure that we can as early as possible rally around a nominee so that we can spend every second that we have making sure that we're working toward that goal," he said.

Barnes said he and Lasry will soon begin campaigning together to "unite Wisconsinites from every corner of the state to defeat Ron Johnson."

"The field is rallying around Mandela Barnes because our real opponent is the insurrectionist Sen. Ron Johnson," said Jake Spence, director of the Working Families Party in Wisconsin. "Now's the time to come together for Mandela so we can flip that Senate seat and deliver the good-paying union jobs, investments in American manufacturing, and support for small businesses that Wisconsin working families deserve."

State Treasurer Sarah Godlewski is the only other Democratic candidate remaining in the race who polled above 1% in a late June poll by Marquette University.

In that survey, 25% of voters said they supported Barnes and 21% said they supported Lasry. Nelson polled at 7% and Godlewski at 9%.

Barnes and Godlewski both beat Johnson in a match-up in the poll, 46-44 and 45-43, respectively.

In the primary race, Barnes differentiated himself from Lasry and Godlewski by relying on small donations ranging from $35 to $40. Lasry's campaign was largely self-funded and Godlewski put $1 million of her personal wealth toward the race.

Barnes has taken aim at Johnson's statements about his personal wealth, including his complaint that he "only" doubled his net worth from $23.76 million in 2011 to about $48 million since taking office.

Johnson "has literally no idea what those of us from working- and middle-class families are going through, and he does not deserve to represent us," Barnes said Wednesday.

Endorsing Barnes last week, Sanders said the lieutenant governor "knows the struggles of the working class" as the son of a public school teacher and a United Auto Workers factory employee.

"His agenda advances the interests of working families, not the billionaire class," said the senator.

Progressive advocate Ilyse Hogue called Lasry's exit from the race "huge news" for the Democratic Party's effort to gain Senate seats.

"Mandela is our best shot to pick up this seat in November and expand the majority with true progressive champs," said Hogue.