CINCINNATI, Ohio – The result of Ohio's Republican Senate primary Tuesday could hinge on whether supporters of former President Donald Trump believe GOP candidate J.D. Vance honestly changed his mind about Trump after being highly critical of him in 2016. 

Trump himself thinks so. The former president endorsed Vance, a former venture capitalist and the author of "Hillbilly Elegy," last month. 

"Like some others, J.D. Vance may have said some not so great things about me in the past, but he gets it now, and I have seen that in spades," Trump said. "He is our best chance for victory in what could be a very tough race."

Ohio GOP Senate candidate J.D. Vance speaks at a rally in Newark, Ohio.

Ohio GOP Senate candidate J.D. Vance speaks at a rally in Newark, Ohio. (Fox News)

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But Ohio GOP voters, who have a menu of five major Republican candidates for their Senate primary – four of whom fought hard for Trump's support – are split on whether they believe Vance's change of heart. 

"Vance, I just don't like how he was a Judas," Claudia Jewett, an undecided voter, told Fox News at a rally for former state Treasurer Josh Mandel, another GOP candidate who sought Trump's support. 

"I think that was a mistake," Mandel supporter Bob Eggers said at the same rally. "But you know what, no one's perfect. I'll still vote for Trump." 

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But Vance supporter Julie Goletz said at a Saturday rally for Vance that meeting him speak in person convinced her to go with Trump's choice in the primary. 

Donald Trump JD Vance

Senate candidate JD Vance, left, greets former President Donald Trump at a rally at the Delaware County Fairgrounds, Saturday, April 23, 2022, in Delaware, Ohio, to endorse Republican candidates ahead of the Ohio primary on May 3.  (AP Photo/Joe Maiorana, File)

"You hear the campaign of the other guy saying that he didn't like Trump," she said. "It's good to hear that he said, ‘Well, that was true, but it’s not true anymore.'" 

"He admitted to saying some of the things that was said on TV," Vickie Boychan, a Vance supporter, said. "He… admitted to it and was sorry for it. That was enough."

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"I needed to hear his thinking, his thought, as to why he switched," Vance supporter Patty Parker said. "But he saw the man, President Trump, and could be, what he stood for and how great he did for our country." 

Vance on the campaign trail is forward about his past comments about Trump. He acknowledges them and says he's genuinely reconsidered his stance. 

The candidate also touts endorsements not only from Trump himself, but also from Donald Trump Jr., Reps. Marjorie Taylor Greene, R-Ga., and Matt Gaetz, R-Fla., and others. 

Reps. Matt Gaetz, R-Fla., and Marjorie Taylor Greene, R-Ga., at a rally for Ohio GOP Senate candidate J.D. Vance in Newark, Ohio.

Reps. Matt Gaetz, R-Fla., and Marjorie Taylor Greene, R-Ga., at a rally for Ohio GOP Senate candidate J.D. Vance in Newark, Ohio. (Fox News)

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"I just think you have to tell the truth. Right? A lot of people change their mind on Donald Trump, and I'm one of them," Vance told Fox News on Saturday. "A lot of our voters don't mind so long as you're just honest with them."

But some voters are still suspicious that Vance is simply behaving like another politician. 

"I was a little confused because I mean I've seen all the things J.D. Vance has said about him," Shelley Pryka, who's undecided, told Fox News at an Ottawa County Republican Women's Club event in Port Clinton. "He said, well, he's changed his mind and liked what Trump did. And that's all well and good. But sometimes I'm afraid that they say that so that you'll vote for them."

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"I was real disappointed to be quite honest, because J.D. Vance never promoted Trump, so I don't know what happened there," Mike Gibbons supporter Sis Bush said the same event. "I was very disappointed in Trump, and I am a Trumpster, okay. But then, he doesn't always get it right either, does he?"

In addition to Mandel and Gibbons, Vance is competing with former Ohio GOP Chair Jane Timken and state Sen. Matt Dolan to make it onto the November ballot. 

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The winner of the GOP primary will likely face Rep. Tim Ryan, D-Ohio, the Democratic front-runner, in November.