BRYN ATHYN, PA – Thanks to a full court press by former President Donald Trump on his behalf, Mehmet Oz is confident he’ll win Pennsylvania’s crowded, divisive, and extremely expensive Republican Senate primary.

"I feel very confident. The light has come out. It’s shining on us," the cardiac surgeon, author, well-known celebrity physician, and first-time candidate told Fox News after voting Tuesday morning in this small and affluent community in Philadelphia’s northern suburbs. "I’m in a very good spot. The polls have been supportive."

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Oz, who until the launch of his Senate campaign late last year was host of TV’s popular "Dr. Oz Show," had been one of the two polling front-runners for a couple of months in the GOP showdown to succeed retiring Republican Sen. Pat Toomey, in a race that may decide whether the GOP wins back the Senate majority in November’s midterm elections.

Dr. Oz votes in Pennsylania primary

Republican Senate candidate Mehmet Oz greets the media after voting in Pennsylvania's primary, on May 17, 2022 in Bryn Athyn, Pennsylvania (Fox News)

Oz has been one of the two combatants in a slugfest with co-front-runner Dave McCormick, a former hedge fund executive, West Point graduate, Gulf War combat veteran and Treasury Department official in former President George W. Bush's administration. Both candidates and others in the jam-packed primary field, worked hard to earn Trump’s endorsement. Trump endorsed Oz last month, held a rally in Pennsylvania with the candidate a week and a half ago, recorded robo-calls for Oz, stars in the candidate’s closing TV ad, and called into Oz’s primary eve rally.

But Trump’s support for Oz did prevent veteran and conservative commentator Kathy Barnette’s from soaring the past month in public opinion surveys — including a Fox News poll — making the Republican primary a three-way face-off.

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Since her surge in the polls, Barnette has faced withering attacks from her rivals and other Republicans concerned over her lack of vetting, past controversial comments, her double-digit loss in a 2020 congressional election, and worries that she’s too extreme to win a statewide general election in a purple state like Pennsylvania.

But Barnette, who voted at a polling station just a couple of miles from where Oz cast his ballot, told reporters she’s "confident" and "I’m so excited we get to make history by the grace of God."

Kathy Burnette votes

Republican Senate candidate Kathy Burnette departs a polling station in Lower Moreland Township, Pennsylvania after voting in the state's primary, on May 17, 2022 (Fox News)

McCormick voted Tuesday morning on the other side of the Keystone State, at a polling station in Pittsburgh.

"I think we're getting good momentum. We feel — we feel great about things," McCormick told reporters after voting. "We feel like voters are focused. As you know, there's lots of undecideds."

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Trump took aim at McCormick and Barnette on primary eve when he called into Oz’s rally. And he emphasized that Oz is "never, ever going to let you down. He's a strong guy, smart gentleman…he's going to be a great senator."

The Oz and McCormick campaigns and outside super PACs backing the two contenders since the beginning of the year have spent tens of millions of dollars to run TV, digital and radio ads attacking each other over their conservative credentials and over key issues.

Dave McCormick votes in primary

Republican Senate candidate Dave McCormick arrives to vote in Pennsylvania's primary, in Pittsburgh, PA on May 17, 2022 (Fox News Madison Scarpino)

Oz, McCormick, and Barnette are part of an eight candidate GOP field that also includes Jeff Bartos, a real estate developer, philanthropist and 2018 Republican nominee for lieutenant governor, and Carla Sands, a real estate executive and major Republican donor who served as ambassador to Denmark during the Trump administration.

With wealthy candidates like Oz, McCormick, Bartos, and Sands able to partially self-fund their campaigns, and with many of the candidates backed by well-financed super PACs, a massive $63 million had been spent by the end of last week to run ads in Pennsylvania’s GOP primary, according to data from the nationally known ad tracking firm AdImpact.

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Without such resources, Barnette by comparison has spent a miniscule amount to run commercials. But Barnette’s bare-bones campaign received some last-minute help from two groups with deep pockets that went up with ads on her behalf — the fiscally conservative Club for Growth Action and the Susan B Anthony List, a leading anti-abortion group.

Barnette told Fox News Digital after voting that even if she loses, "I will" endorse whoever wins the GOP Senate primary.

Barnette’s rise in the polls may have been partially fueled by her alliance with Sen. Doug Mastriano, the polling front-runner for Pennsylvania’s GOP gubernatorial primary. The two have held joint rallies, with reporters barred from covering their joint appearance this past weekend.

Doug Mastriano Pennsylvania

Pennsylvania state Sen. Doug Mastriano, R-Franklin, a Republican running for Governor of Pennsylvania, meets supporters at a campaign stop Tuesday, May 10, 2022, in Portersville, Pa. (AP Photo/Keith Srakocic)

Mastriano worked to try and help overturn Trump's narrow 2020 loss in Pennsylvania to now-President Biden, and was outside the U.S. Capitol when it was stormed on Jan. 6, 2021, by right-wing extremists aiming to disrupt congressional certification of Biden's Electoral College victory. And both Mastriano and Barnette — who was also in Washington, D.C., that day — continue to support Trump's unproven claims that the 2020 election was "stolen" due to "massive voter fraud" and support the former president's efforts to repeatedly re-litigate his election loss.

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Some Pennsylvania Republicans are concerned that having someone as far to the right as Mastriano as their gubernatorial standard bearer in November’s general election will hurt Republicans in the Senate election and in down ballot races.

But Oz told Fox News Digital that if he wins the GOP Senate primary, he’ll campaign in the general election with Mastriano.

Pennsylvania Senate candidate Mehmet Oz, left, accompanied by former President Donald Trump speaks at a campaign rally in Greensburg, Pa., Friday, May 6, 2022. (AP Photo/Gene J. Puskar)

Pennsylvania Senate candidate Mehmet Oz, left, accompanied by former President Donald Trump speaks at a campaign rally in Greensburg, Pa., Friday, May 6, 2022. (AP Photo/Gene J. Puskar) (AP Photo/Gene J. Puskar)

"I can rally with Mastriano. I can rally with other Republicans. I don’t have to align 100% with people, with their own personal views. I have to make sure directionally we’re going in the right spot," Oz said. 

And taking aim at the president, Oz stressed "I think the only thing Joe Biden is building back better is the Republican Party. He’s pushing us together, unifying us in ways otherwise probably not that imaginable."

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The winner of the GOP Senate primary will likely face off in November against Lt. Gov. John Fetterman, the clear front-runner in the race for the Democratic Senate nomination. Fetterman won’t be attending his primary night event, after announcing on Sunday that he had suffered a stroke two days earlier and had been hospitalized.

But Fetterman said that he’s "well on my way to a full recovery" and added that his "campaign isn’t slowing down one bit."

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In the race to succeed term-limited Democratic Gov. Tom Wolf, Democrats have coalesced around state attorney general Josh Shapiro in their primary.

Fox News’ Bryan Llenas, Courtney De George, Madison Scarpino, and Emmett Jones contributed to this report