Also running is Kathy Barnette, a political commentator who has written a book about being Black and conservative and has raised more than $1 million.
Limited public polling shows a wide-open contest. A Fox News survey in early March showed Mr. McCormick leading, with 24 percent, and Dr. Oz at 15 percent, but many voters were undecided. The Democratic field includes Lt. Gov. John Fetterman, Representative Conor Lamb and Malcolm Kenyatta, a state representative.
The pro-Trump label can be an awkward fit for both Mr. McCormick and Dr. Oz.
Mr. McCormick is the former chief executive of the Bridgewater hedge fund and served in the Treasury Department of the second Bush administration. His career arc from West Point graduate to the financial world more neatly fits the traditional Republican establishment mold, and he said last year that the riot on Jan. 6 at the Capitol was “a dark chapter in American history.”
For his part, Dr. Oz first found fame as a regular guest on “The Oprah Winfrey Show,” and clips showing him dancing with Michelle Obama have made their way into ads attacking him. He previously supported key elements of the Affordable Care Act and, while he calls himself “pro-life,” he struggled in a Fox News interview to articulate when he believes life begins.
Mr. Trump, according to advisers, has tracked the race closely but appears content — for now — to sit on the sidelines. He jealously guards his endorsement record and was already burned by his early backing of Mr. Parnell. Facing the possible defeat of candidates he is backing in other states, Mr. Trump has turned at least temporarily more cautious in some key Senate races.
Just as he is doing in two other crowded Republican primaries, in Ohio and Missouri, Mr. Trump is not picking sides while the field remains muddled. In both those states, he has also met with multiple candidates vying for his backing.
Rob Gleason, a former chairman of the Pennsylvania Republican Party, said a Trump endorsement in the state’s race “could be the tipping point in a close election.
“He’s just very important in Republican circles,” he said. “He still is.”