“I didn’t like Trump six years ago,” he told a small crowd of supporters this week at a brewery in Hilliard. “I did not think he was going to be a good president. I was very happy to be proven wrong.”
He added, “I was very proud to support the president over the past several years.”
Mr. Trump is said to have been moving toward Mr. Vance for some time, according to the four Republicans familiar with his advisers’ discussions. He has been encouraged by a range of allies and donors, including the billionaire Peter Thiel, who is a primary financial backer of Mr. Vance. The Fox News host Tucker Carlson, who is influential with members of Mr. Trump’s base, has also spoken favorably about Mr. Vance on his prime-time show.
Mr. Vance’s opponents began attacking him over his lack of Trump fealty early, and have spent nearly $2.8 million in television and digital ads since February, according to an analysis by the media tracking firm AdImpact.
Many Republicans in Ohio have been waiting for Mr. Trump to endorse a Senate candidate, saying it would help them make a decision. But with voting already underway, some voters at Republican events this week had already cast their ballots or had at least made up their minds.
At a gathering for Ms. Timken in Athens on Thursday, at least one voter said Mr. Trump’s backing was significant but not a game changer. “If she wasn’t a Trump supporter, I probably wouldn’t support her,” said Amy Karr, 50, an accountant in Racine. But Ms. Karr said she planned to vote for Ms. Timken regardless of whom Mr. Trump endorsed.
Ms. Timken said she was the only Republican candidate for Senate whom the former president had endorsed in the past, when she was in the running for chair of the Ohio Republican Party.
“I know there’s rumors swirling around, but there seems to be rumors swirling around all the time,” she said. “Look, President Trump is very popular with Republican primary voters. But every day I’m out earning the vote of Ohioans, and they’re the ones who are going to make this difference in this race.”
Jazmine Ulloa reported from Columbus, Ohio, and Maggie Haberman from New York.
