Republicans in Pennsylvania expected that the entry of such a high-profile figure into the Senate race, one who is promising to spend large sums of his own fortune, would shake up a field without a front-runner. It follows the recent withdrawal of Sean Parnell, the Trump-endorsed candidate, who suspended his campaign after a judge gave primary custody of his children to his estranged wife, who had accused him of abuse.
A number of Republican officials, whom Dr. Oz has been calling in recent weeks, said they thought voters would take the celebrity physician seriously.
“The first thing I asked was, ‘Why are you running? Is this a vanity play?’” said Sam DeMarco III, the Republican chairman of Allegheny County, which includes Pittsburgh. But he said he was impressed with Dr. Oz’s seriousness in response to his questions. “My most important goal is to keep this seat in Republican hands come 2022, and I believe Dr. Oz’s entry into the race gives us a significant opportunity to do that,” Mr. DeMarco said.
For Democrats, Pennsylvania represents perhaps their best chance to add a Senate seat to their column, since it is the only open seat next year in a state that President Biden carried in 2020. Senator Patrick J. Toomey, a Republican, is not seeking re-election.
While the Democratic field has several seasoned candidates, including Lt. Gov. John Fetterman and Representative Conor Lamb, the Republicans in the race are less experienced and, with the exception of Dr. Oz, less well known.
Most have leaned into their connections to Mr. Trump to win favor with a party base that fervidly supports the former president, including his false claims that he won the state last year. Jeff Bartos, a real estate developer, has called for a “full forensic audit” of the 2020 election in the state. Kathy Barnette, a former financial executive, has pushed claims of voter fraud on Newsmax and OAN. David McCormick, the chief executive of Bridgewater Associates, a giant hedge fund company, has been exploring getting into the race as well.