COLUMBUS, Ohio (WCMH) — Donald Trump’s support seems to be making the difference for JD Vance, according to the first independent poll of Ohio’s Republican U.S. Senate race after the former president endorsed Vance.

A Fox News poll conducted last week shows Vance with 23% of likely voters, although more voters (25%) are still undecided. It’s the Cincinnati-area author and venture capitalist’s first lead in the race, which has had nonpartisan polling since December.

Behind Vance are former state treasurer Josh Mandel (18%), Cleveland banker Mike Gibbons (13%), state Sen. Matt Dolan (11%), and former Ohio GOP chair Jane Timken (6%).

Vance had been mostly in a distant third place behind Gibbons and Mandel in past polls, but Trump’s endorsement about two weeks ago catapulted him to the lead. Trump formally endorsed Vance at a rally in Delaware County on Saturday.

“The race is obviously close, and this is clearly a case in which an endorsement has made a difference,” Republican pollster Daron Shaw, who conducts Fox’s surveys with Democratic pollster Chris Anderson, told Fox News.

Fox’s poll was conducted April 20-24 among 906 likely voters, but it has a 3-point margin of error that shows Vance’s lead isn’t watertight.

The 3-point error margin, in theory, gives each candidate a 6-point swing in their advantages, meaning a repolling could theoretically put Mandel over Vance, 21% to 20%.

For most polls, you can read the margin of error (MoE) like this: If the poll were to be done again 100 times, in 95 of those times the results would be within “X” percentage points of the original.

So let’s say a national poll of a sampling of registered voters, with an MoE of +/- 3, has:

  • Joe Biden at 53%
  • Donald Trump at 47%

  • You can be 95% certain that a hypothetical poll of all registered U.S. voters would yield results between these extremes:

  • Biden 56/Trump 44 (+3 more for Biden, -3 fewer for Trump)
  • Trump 50/Biden 50 (+3 more for Trump, -3 fewer for Biden)
  • But in such a crowded primary, Shaw says, any lead is noticeable.

    "With support spread out among five candidates who are pretty similar in policy terms," Shaw told Fox News, "the bump that comes with Trump’s blessing is enough to jump Vance to the head of the pack."