Former US president Donald Trump will put his endorsement to the test once again at a rally in Pennsylvania on Friday to support celebrity surgeon Dr Mehmet Oz's campaign for a seat in the US Senate in a closely watched Republican primary.
Mr Trump secured his first proxy win of the 2022 midterm campaigns on Tuesday after Hillbilly Elegy author JD Vance won the Republican primary in Ohio.
But the Pennsylvania election could prove the most consequential in determining which party controls the US Senate — and Dr Oz faces stiff competition among Republicans to replace retiring senator Pat Toomey.
The former president narrowly lost the state to President Joe Biden in the 2020 election.
Mr Trump’s endorsement of Dr Oz prompted some people to take another look at him, but also sparked confusion over the former president’s choice, said Bill Bretz, chairman of the Republican Committee in Westmoreland County near Pittsburgh, where Mr Trump is holding the rally for Dr Oz.
A former reality television star himself, Mr Trump has said Dr Oz has proved his popularity through his long-running programme and has the best chance to win in the November election.
Dr Oz became a household name thanks to a series of appearances on The Oprah Winfrey Show, later going on to star in his own series.
Other conservatives joining Mr Trump at Friday's rally include MyPillow chief executive Mike Lindell and Mr Vance.
Mr Trump is very popular among Republican primary voters and he has helped Dr Oz’s campaign “tremendously” despite his opponent, David McCormick, a chief executive and hedge fund investor, spending more than $15 million on attack ads, Dr Oz's spokeswoman Brittany Yanick said.
The escalating vitriol is targeted on the celebrity heart surgeon’s connections to his parents’ native country of Turkey, raising it as a possible national security issue. If elected, Oz would be the nation's first Muslim senator.
But even though he is currently leading in the Republican polls, Dr Oz has faced questions over his conservative credentials on issues such as abortion and gun control, said Kristin Davison, a Republican consultant for Mr McCormick, who also consulted for defeated Senate primary candidate Josh Mandel in Ohio.
“In Pennsylvania, you see more voters saying, ‘We love the president, but this guy’s not a Republican. We just can’t get there with him,’” Ms Davison said.
Abortion rights have been thrust back into the political spotlight after a leaked document revealed the Supreme Court's plans to overturn the 1973 Roe v Wade ruling that legalised abortion.
The leaked document spurred Democrats, including Mr Biden and Vice President Kamala Harris, to urge supporters to elect pro-life officials in November.
Bloomberg contributed to this report