Ohio GOP Senate candidate Josh Mandel fended off attacks from an opponent calling him a "phony, fraud and sell-out" and stumped with political supporters at a packed auditorium of the Victory Christian Church in Kettering, Ohio, Friday.
Trump-endorsed candidate J.D. Vance accused Mandel of being a Republican in name only (RINO) following reports from an upcoming book that Mandel pretends to be pro-Make America Great Again on the campaign trail but sides with establishment Republicans in private.
"I think people in Washington will make false attacks all the time on people like me because I'm a constitutional conservative and a fighter," Mandel told Fox News Digital at the rally, responding to Vance's comments. "People can call me a lot of names, doesn't make it true."
New York Times reporters Jonathan Martin and Alex Burns briefly described Mandel, a former Ohio state treasurer, of speaking out of both sides of his mouth when it came to supporting former President Donald Trump over establishment Republican leaders like Senate Minority Leader Mitch McConnell, R-Ky.
"Mandel, acknowledged to Republicans in Washington that he was parroting absurd rhetoric in the primary campaign out of a desire to court Trump and his supporters — but that was simply what he believed it would take to win," Burns and Martin wrote in their book "This Will Not Pass," which will be released May 3.
"In fact even as he publicly mimicked Trump's incendiary rhetoric, Mandel would privately reach out to McConnell's top lieutenants to alert them each time one of his top rivals, J.D. Vance, criticized Washington Republicans — effectively trying to have it both ways with Trump and the GOP leaders he derided."
In a statement Friday, Vance spokesperson Taylor Van Kirk said the excerpts from the book reveal Mandel "claims to be ‘anti-establishment in public, but throws President Trump and the entire MAGA movement under the bus to the establishment behind closed doors."
"While JD Vance was courageously criticizing GOP leadership and holding them to account for their failures, Mandel was quite literally kissing the ring and bending the knee to the RINO establishment. Josh is a cowardly political chameleon who simply cannot be trusted to put America First," Van Kirk said.
Mandel and candidate Mike Gibbons, an investment banker, were considered the top tier candidates in the Ohio GOP Senate primary for most of the race, up until Trump endorsed Vance earlier this month. A Fox News poll released Tuesday showed Vance at 23% compared to Mandel at 18% and Gibbons at 13%, with many likely voters still undecided.
Mandel told Fox News Digital Friday that he was former Ohio Gov. John Kasich's "worst nightmare." Mandel said he opposed the former Republican governor over Obamacare expansion in Ohio, financial transparency, and disapproved of Kasich's attempts to block pro-life legislation.
"I think the people here in Ohio, the conservative grassroots, know that there's only one fighter, only one true conservative in this race — and it's me, Josh Mandel," he said, flanked by Sen. Ted Cruz, R-Texas.
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Cruz, who stumped for Mandel Friday, agreed. "If you look at Josh's record, he's got the strongest conservative record of standing and fighting for conservative principles," Cruz told Fox News Digital.
"A lot of the people running against me, a lot of the folks in the media, in the squishy, RINO, establishment wing of the party, they think America first is a slogan. It's not a slogan, it's a governing philosophy. And I'm the only one who gets that," Mandel said.
Implementing America first principles at the border, for example, "means securing the border and deporting every single illegal in this country — not because we hate foreigners, but because we love this country," Mandel said.
Before the rally, attendees told Fox News that they liked what they hear from Mandel, including his faith and his Marine Corps service.
Several attendees said they support Trump, but are dissatisfied with his endorsement of Vance. One said it was a "mistake." Another called Vance a "Judas." One attendee said they believe Vance, if he wins the GOP nomination, might make a general election move to the left, leaning on his past criticism of Trump as he runs against a Democrat.
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During his speech, Mandel touted his focus on churches during the campaign to applause from the audience. He touted large crowd numbers he attracted at churches throughout Ohio.
Mandel also called out anti-Trump Republican Reps. Liz Cheney of Wyoming and Adam Kinzinger of Illinois, as well as Sen. Mitt Romney, R-Utah, saying: "we need to do everything we can to eliminate them from the Republican Party and from politics."
The Ohio Republican Senate primary will be held May 3.
Fox News' Mark Meredith contributed to this report.