A grass-roots organizer and climate activist prevailed in the Democratic primary for a battleground House district in Michigan on Tuesday, according to The Associated Press, scoring another victory for the party’s progressive wing in a district pivotal for the fight to control Congress.

The organizer, William Lawrence, 35, a co-founder of the Sunrise Movement, a youth-led environmental group, defeated two more moderate candidates to advance to the general election against Representative Tom Barrett, a first-term Republican seen as one of the most vulnerable incumbents.

Backed by Senator Bernie Sanders of Vermont, Mr. Lawrence centered his campaign on opposing data centers, increasing taxes on billionaires and passing legislation for universal health care. He also said he would end arms sales to Israel.

The Lansing-area district in Central Michigan, the Seventh Congressional, is one of only 18 House seats rated as tossups by the nonpartisan Cook Political Report, and Democrats see it as one of their best chances for a flip in November. Some Democrats worried that the two moderate candidates would split the vote and that Mr. Lawrence’s views would pave the way for Mr. Barrett, an Army veteran who flipped the district in 2024, to win re-election.

Senator Elissa Slotkin, who previously held the seat before ascending to the upper chamber, endorsed one of Mr. Lawrence’s opponents, Matt Maasdam, a retired Navy SEAL and former military aide in the Obama administration. In doing so, she spurned Bridget Brink, the other moderate candidate, who was appointed ambassador to Ukraine by President Joseph R. Biden Jr. and, once President Trump took office, quit in protest of his cozy relationship with Russia.

Mr. Maasdam said that a shadowy PAC’s ads attacking him and promoting Mr. Lawrence were evidence that Republicans would rather face him than a moderate in the fall. The group has not yet disclosed its donors, but Republican PACs have meddled in a series of Democratic primary races this year. It uses a little-known South Dakota bank that has been linked with G.O.P. operatives.

Mr. Lawrence’s campaign disputed that his views would turn off swing voters, saying he was in touch with the concerns of Michiganders.

“I think anyone who has concerns should come out and knock on doors,” Mr. Lawrence told The New York Times over the weekend. “What they’ll hear is people are furious about data centers. Trump voters are getting off the Trump train because of Iran. Nobody could afford the essentials. They’re sick of corporate-funded politicians. That’s why we’ve built the momentum.”

During the campaign, Mr. Lawrence faced a backlash over a comment he made in 2024 that an older generation of Black Democratic leadership “defangs the white left.” He said he regretted the remark.

He does not identify as a democratic socialist, he told The Times, but his campaign has confirmed that he was previously a member of the Democratic Socialists of America. The group has not endorsed him.

On the campaign trail, Mr. Lawrence slammed “corporate-funded candidates,” pointing to his pledge to reject corporate PAC money.

Simultaneously, however, his website featured a public page containing specific messaging directives for advertisers. The practice — commonly called “redboxing” — helps candidates signal their preferred talking points to independent political action committees without violating federal campaign finance laws against direct coordination.