Since Mr. Lasry mostly paid for his own campaign to run against Sen. Ron Johnson, his departure opens the door for Lt. Gov. Mandela Barnes to get the Democratic nomination.

Alex Lasry, a manager for the Milwaukee Bucks who mostly paid for his own campaign for the Senate in Wisconsin, dropped out of the Democratic primary on Wednesday.

Mr. Lasry, who is 35 years old and whose billionaire father is a co-owner of the Milwaukee NBA team, spent more than $12 million on his primary campaign, but he never got more votes than Mr. Barnes

With less than two weeks until the state’s primary on August 9, Mr. Lasry decided he couldn’t win. Mr. Lasry said on Wednesday that it has become clear in the last few weeks

At an event outside the Bucks’ arena in downtown Milwaukee on Wednesday afternoon, Mr. Lasry gave Mr. Barnes his full support. The Milwaukee Journal Sentinel was the first to write.

The Democratic base hates Mr. Johnson because he spreads false theories about the coronavirus pandemic and wants to change the results of the 2020 election.

The Democratic primary was pretty calm, with few negative attacks and little bad blood between the candidates. But Mr. Barnes, who is 35 years old, has plenty of political weaknesses of his own.

At one point, he wore a shirt that said “Abolish ICE,” and more recently, he fought against the Biden administration’s plan to end Title 42, a policy put in place by Trump during the pandemic

that was used to turn away migrants at the Mexican border. In an earlier version of this article, there was a mistake about Mandela Barnes and a shirt that said: “abolish ICE.