Updated

NEWTOWN, PA – The razor-thin race between Pennsylvania Senate GOP frontrunners Mehmet Oz and Dave McCormick may be headed for a recount as the candidates sit just tenths of a percentage point apart in election night returns as of early Wednesday morning. 

The automatic recount threshold in Pennsylvania is 0.5%. That means depending on where any still-outstanding ballots fall, voters could be waiting days more to find out who will face Democrat nominee Lt. Gov. John Fetterman in the open-seat race that's crucial to control of the U.S. Senate. 

"So we're not going to have a result tonight. When all the votes are tallied, I am confident we will win," Oz told supporters at his election night party.

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. (Fox News)

"We are going to win this campaign," McCormick said. "Right now we have tens of thousands of mail-in ballots that have not been counted... unfortunately we're not going to have resolution tonight. But we can see the path ahead, we can see victory ahead."

Oz and McCormick survived a bruising exchange of attack ads and a late charge by fellow candidate Kathy Barnette, a conservative commentator who surged in opinion polls shortly before Election Day.

Fetterman Tuesday took the Democratic Senate nomination despite a stroke last week. He beat moderate Rep. Conor Lamb, D-Pa., in a victory for progressives in the Keystone State. 

While former President Donald Trump wasn't on the ballot on Tuesday, his continued firm grip over the GOP is on the line in the Republican Senate showdown, following his endorsement and full court press of support the past week and a half for Oz.

Dave McCormick votes in primary

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

Also grabbing national attention in Pennsylvania was Sen. Doug Mastriano — a strong supporter of Trump’s repeated attempts the past year and a half to relitigate his 2020 election loss, who was endorsed by the former president just three days ago. That could potentially cause the GOP major headaches in the general election.

The Associated Press called the gubernatorial race for Mastriano Tuesday night.

"Big night for Doug Mastriano!" Trump wrote on his social network Truth Social Tuesday night. 

TRUMP'S GOP CLOUT IS ON THE LINE IN PENNSYLVANIA'S REPUBLICAN SENATE PRIMARY

And the spotlight’s also shining on state Rep. Summer Lee, a progressive lawmaker who’s running in the Democratic primary for an open U.S. House seat in a heavily blue Pittsburgh-area congressional district. 

Lee, who enjoys the backing of giants on the Left — including Sens. Bernie Sanders and Elizabeth Warren, and Rep. Alexandria Ocasio Cortez — could become the latest member of the so-called "Squad" of diverse, progressive House members if she wins the primary election. Her divisive primary against opponent Steve Irwin has turned into a battle between the Democratic Party’s centrist and progressive wings, and remains undecided early Wednesday.

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Meanwhile, the Democratic nominees for Senate and governor were making headlines on primary day due to their health. Fetterman's campaign said he was undergoing what they called a "standard procedure" to implant a pacemaker with a defibrillator after he suffered a stroke on Friday and was hospitalized. Fetterman – whom the AP projected to win the Democratic Senate nomination Tuesday – said on Sunday that he was on the way to "a full recovery" and added that his "campaign isn’t slowing down one bit."

Pennsylvania Attorney General Josh Shapiro, whom the Associated Press projected to win the Democratic gubernatorial primary Tuesday, tested positive for COVID-19 on primary morning.

"After 8 years of the disastrous policies of Tom Wolf, Republican voters in Pennsylvania have chosen Doug Mastriano as their nominee for Governor," Republican Governors Association executive director Dave Rexrode said Tuesday. "The country, and Pennsylvania, is worse off under Democratic leadership and Josh Shapiro, who will continue the same policies that have led to record inflation and increased violent crime."

"Instead of focusing on kitchen-table issues like strengthening the economy and investing in education, Doug Mastriano is an extremist running on a dangerous agenda that would devastate Pennsylvania families," Democrat Governors Association Executive Director Noam Lee said. "He led the charge to overturn Pennsylvania’s 2020 election results, bused people to the deadly attack on the U.S. Capitol, and has even been subpoenaed by the bipartisan January 6th committee."

State Sen. Doug Mastriano, a Republican candidate for governor, speaks at a primary night election gathering in Chambersburg, Pennsylvania, Tuesday, May 17, 2022. (AP Photo/Carolyn Kaster)

OZ, BARNETTE, MCCORMICK CAST BALLOTS IN CRUCIAL GOP SENATE PRIMARY

Oz, the cardiac surgeon, author and well-known celebrity physician, who until the launch of his Senate campaign late last year was host of TV’s popular "Dr. Oz Show," told Fox News after casting his primary ballot that he felt "very confident" and that he was "in a very good spot."

Oz has been one of the two polling front-runners for a couple of months in the GOP showdown to succeed retiring Republican Sen. Pat Toomey, along with 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.

McCormick highlighted his "good momentum" and pointed to the high percentage of voters who said their minds were still not made up heading into the primary. He noted that "there’s lots of undecideds."

INTRA-PARTY BATTLES IN THE SPOTLIGHT IN KEY HOUSE PRIMARIES FROM COAST TO COAST

The Republican primary turned into a three-way face-off in the past few weeks following a surge of support in public opinion polls for veteran and conservative commentator Kathy Barnette. An optimistic Barnette told reporters she’s "so excited we get to make history by the grace of God."

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

Among the other major contenders in the large GOP primary field were 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.

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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, making the GOP primary the most expensive in the nation so far this cycle.

After her jump in the polls, Barnette 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.