COLUMBUS, Ohio (WCMH) — As the remaining undecided voters pick their candidates, three Republican U.S. Senate candidates have emerged as the final frontrunners in a major pollster’s last poll before Ohio’s primary election Tuesday.

JD Vance, the author and venture capitalist supported by former President Donald Trump, continues his strong post-endorsement performance by leading the Trafalgar Group’s final poll of the race with 26% of the vote.

But Vance’s closest challenger is not Josh Mandel or Mike Gibbons, the pre-endorsement frontrunners, but state Sen. Matt Dolan, the only candidate Trump said he wouldn’t endorse.

Mandel, a former state treasurer and the 2012 Republican Senate nominee, polled close behind Dolan in third with 21%. Gibbons, an investment banker, was fourth with 13%, and former Ohio GOP chair Jane Timken was fifth with 6%.

Other candidates Mark Pukita and Neil Patel, two Columbus-area business owners, polled at a distant 2% each. Just under 1 in 10 likely voters are still undecided.

Vance, Dolan, Mandel the final frontrunners

The Trafalgar poll was conducted April 29 through May 1 among 1,081 likely GOP primary voters. Its margin of error is about 3 percentage points, which mathematically puts Vance, Dolan and Mandel in contention for the lead, because each candidate’s advantage could swing by 6 points if the poll were conducted again.

Dolan, for example, could gain 3 points in a hypothetical repolling, and Vance could lose 3 points, which would produce a mathematically possible Dolan win of 25% to 23% over Vance.

Released overnight Monday, Trafalgar’s poll is their fourth of the race after surveys in mid-December, early February and mid-April. Undecideds dominated the first two polls, and Mandel led Vance in the third one.

Emerson College completed a survey on Friday that also showed Dolan with a late surge: 18% of likely voters behind Mandel (22%) and Vance (24%).

Additionally, a late April poll conducted by Democratic pollster Blueprint Polling, put Dolan in the lead with 18%, ahead of Vance (17%) and Gibbons (13%). More than 3 in 10 voters, however, were still undecided in that poll.

While every other candidate openly sought Trump’s endorsement for Tuesday’s primary, Dolan, a state lawmaker from Chagrin Falls, argued he championed Trump-like conservative policies in the legislature.

Dolan is seen as a more center-right choice in the race, and he was the only candidate at debates to say Trump should move on from his loss in 2020 instead of repeat disproven claims of widespread voter fraud.

Trump has rejected Dolan twice in public statements, complaining that his family — who owns the Cleveland Guardians baseball team — should not have changed its name from the Indians. Last week, Trump said Dolan “is not fit to serve” in the Senate because of that.

The former president endorsed Vance on April 15 and enthusiastically featured him at a rally in Delaware County a week later. But Trump also mixed up Vance’s name at a Sunday rally in Nebraska.

“We’ve endorsed J.P., right? J.D. Mandel and he’s doing great,” Trump said.

How reliable is Trafalgar polling?

Although polling from the Atlanta-based pollster tends to favor Republicans, and the group has been criticized for not explaining its methodology in great detail, it was among the most accurate pollsters of Ohio in the 2020 presidential election.

Trafalgar correctly predicted former President Donald Trump would win Ohio last year, as a poll days before the election favored him over President Joe Biden by 4.8 percentage points. And that poll’s margin of error was just 2.96 points. Trump won the state by just over 8 points.

The pollster notes on its website that it uses a mix of techniques like live calls, texts and emails to conduct polls. Its surveys are also shorter and try to accommodate for a recent trend of respondents intentionally giving false answers because of who is asking and why.

Trafalgar correctly predicted Trump winning the presidency in 2016, and FiveThirtyEight rated it the second most accurate pollster for the 2020 election despite it predicting a Biden loss. The poll-tracking website gives Trafalgar an overall A-minus rating.