FORMER US PRESIDENT Donald Trump has given his backing to celebrity doctor Dr Oz and encouraged him to declare victory in a narrow Pennsylvania Republican Senate primary.

With over 95% of votes counted Dr Oz, whose real name is Mehmet Cengiz Öz, leads with 31.2% of the vote, compared to 31.1% for challenger Dave McCormick.

A New York Times tally had the lead at just over 1,200 votes out of 1.1 million Republican votes cast in the primary, and there are estimated to be thousands of mail-in votes that could take weeks to count.

Pennsylvania law mandates an automatic recount if a margin of victory is 0.5% or less. 

Despite this, Trump has urged the Turkish-American doctor to declare victory in the race for the Republican party nomination.

Trump took to Truth Social, his new social media platform, yesterday to cast doubt on the election and claim that Dr Oz, a surgeon best known for his appearances on the Oprah Winfrey Show, had won.

He compared the state’s counting of mail-in ballots to the 2020 election, which he continues to insist he won.

“Here we go again,” Trump said of the primary.

“In Pennsylvania, they are unable to count the mail-in ballots. It is a big mess.”

In another post, he said: ”It just makes it harder for them to cheat with the ballots that they ‘just happened to find’”.

Midterm elections take place in the US two years into a president’s term and decide which party controls the Senate and House of Representatives, the two legislative chambers that collectively make up Congress.

The winner of the primary will face John Fetterman, the state’s lieutenant governor who overwhelmingly won the Democratic nomination.

Pennsylvania is considered a key battleground state in the upcoming midterms. 

On Tuesday Dr Oz thanked both Trump and Fox News television host Sean Hannity for their support of his campaign.

“President Trump after he endorsed me continued to lean into this race in Pennsylvania,” Dr Oz said. “God bless you, sir, for putting so much effort into this race. I will make you proud.”

Dr Oz is a longtime resident of New Jersey, but according to the Associated Press, he registered to vote by absentee last year from his in-law’s address in the Philadelphia suburbs, which qualified him to run the in the state this year.