Bernie Moreno, a wealthy former car dealer and political newcomer, rode the endorsement of former President Donald J. Trump to victory on Tuesday in a hotly contested primary to determine which Ohio Republican would take on incumbent Senator Sherrod Brown, the last Democrat to hold elective statewide office in the increasingly Republican state.
Mr. Moreno beat State Senator Matt Dolan, whose family is a majority owner of the Cleveland Guardians baseball team, and Frank LaRose, Ohio’s secretary of state, once again proving the power of Mr. Trump’s backing among Republican primary voters. Rarely has a contest so clearly divided the old-line Republican establishment from the new Trump wing of the party, and again, the former president’s movement prevailed.
“We’re the party of the future,” declared Mr. Moreno, who would be one of the Senate’s richest members, and its only South American-born member, if elected in November. “We’re the party that’s going to rebuild the middle class in this country.”
Mr. Brown answered, “The choice ahead of Ohio is clear: Bernie Moreno has spent his career and campaign putting himself first and would do the same if elected. Elections come down to whose side you’re on, and I’ll always work for Ohio.”
It was, for Mr. Trump, another triumph. For Mr. Dolan, it was a second loss to a Trump-backed political neophyte. In 2022, the author and investor J.D. Vance beat him in the primary race for retiring Senator Rob Portman’s seat and went on to win the general election that fall.
In stumping for Mr. Dolan, Mike DeWine, Ohio’s Republican governor, tried to make the case that Mr. Dolan was the best candidate to take on Mr. Brown, whose blue-collar appeal and well-established political persona could be tough to beat, even in a state where Mr. Trump won the last two presidential elections by more than eight percentage points each time.
But in the Trump era, electability has rarely beaten fealty when the former president has gotten involved. Mr. Moreno flooded Ohio airwaves with advertisements attacking Mr. Dolan for what he called an insufficient level of support for Mr. Trump’s border policies. Mr. Trump rallied voters for Mr. Moreno over the weekend outside Dayton, making headlines for saying some migrants were “not people” and, amid a discussion of the auto industry, predicting “a blood bath” if he lost in November.
Mr. Moreno will enter the general election depleted of cash and bruised by an extremely negative primary campaign that ended with a super PAC backing Mr. Dolan airing allegations from an Associated Press report that he had once advertised on an adult website for male dates. Mr. Moreno’s campaign said the adult website profile was created in 2008 by an intern as a prank.
Of the $9.7 million that Mr. Moreno has raised for his run, less than $2.4 million remained at the end of February, according to campaign finance reports.
A Democratic super PAC aired advertisements in the closing days of the primary to elevate Mr. Moreno, clearly indicating that he was the candidate the party wanted to take on in November.
That same organization, the Senate Majority PAC, immediately castigated the candidate it had elevated, saying in a statement that Mr. Moreno “won’t be able to hide from the fact that he is a shady car salesman.” The Democratic Senatorial Campaign Committee attacked him immediately as well, recycling videos of attacks from Mr. Dolan and Mr. LaRose that tarred the newly minted nominee as an untrustworthy, corrupt extremist.
The Senate Republicans’ political arm framed the race differently. “Bernie is a political outsider running against a liberal career politician who has been running for office for 50 years,” said Senator Steve Daines of Montana, who chairs the National Republican Senatorial Committee.
Mr. Brown enters the general election primed, rested and ready. He has raked in money not only from unions that are steadfastly loyal to him but also from corporations that have business before the Senate Banking Committee, which he chairs. His campaign has raised at least $26.7 million this election cycle, and has more than $13.5 million cash on hand.
But Mr. Moreno will be running in a state that has become increasingly hostile to Democrats — and that President Biden is unlikely to contest seriously as he campaigns for another term.
Mr. Brown, who was first elected to the Senate in 2006, evinced little concern over his third re-election bid. The Democrat has made his reputation as a pro-worker politician who has stood against free-trade agreements and stood for unions in a state where the working class has drifted to the G.O.P. since Barack Obama won it twice.
“We will spend this campaign contrasting my position on taking on Wall Street, my position on taking on the drug companies, my position on trade with theirs,” he told reporters on Monday in Dayton, Ohio.
Ohioans did vote last November to enshrine abortion rights in the state’s Constitution and to legalize marijuana, votes that Mr. Brown says show a political complexity that defies clear partisan division.
With control of the Senate within Republicans’ reach, Ohio and Montana — the only states where Mr. Trump won in 2020 and a Democrat is standing for re-election — promise to gain huge national attention. Democrats hold 51 Senate seats, but one of those, in deep-red West Virginia, is virtually gone with the retirement of the conservative Democrat Joe Manchin III.
The Senate Leadership Fund, a super PAC aligned with the Senate Republican leadership, and an allied group, American Crossroads, have already reserved nearly $83 million worth of advertising time this fall in Ohio.