HARRISBURG — The Republican field of candidates aiming to capture Pennsylvania's open U.S. Senate seat in next year's election is churning anew, with the candidate endorsed by former President Donald Trump out and intriguing new candidates possibly in.

Out is Sean Parnell who ended his campaign after losing a custody battle in court in which the judge said he believed allegations of abuse made by Parnell's estranged wife.

“With the leading candidate getting out, that's certainly going to create a reshuffling of the race here,” said Sam DeMarco, the chair of the Allegheny County Republican Party.

The high-stakes campaign to replace retiring Republican Sen. Pat Toomey in the battleground state could determine control of the Senate in next year's election.

Who might get in? Maybe a couple guys who are relative unknowns to many party figures but are otherwise prominent in their own fields.

First, there is Mehmet Oz, the cardiac surgeon and host of TV's “Dr. Oz Show” who gained fame as a protege of Oprah Winfrey. The longtime New Jersey resident now says that he has lived in Pennsylvania since last year.

The other is David McCormick, a Connecticut resident who runs one of the world's largest hedge funds, Bridgewater Associates, but grew up in Pennsylvania as the son of a former chancellor of the Pennsylvania State System of Higher Education.

Here's a look at the landscape:

The Republicans

The most prominent Republicans already running are conservative commentator Kathy Barnette, real estate investor Jeff Bartos and Carla Sands, Trump's ambassador to Denmark.

Of them, none has won elective office before, and only Bartos has run statewide in Pennsylvania.

Bartos is perhaps best-known to party members after winning the nomination for lieutenant governor in 2018 and running with gubernatorial nominee Scott Wagner on the unsuccessful ticket.

The Democrats

The Democratic field has been stable since August, and features candidates with far more electoral experience — although far less personal wealth — than the Republican field.

An early entrant was John Fetterman, the state's lieutenant governor. He ran unsuccessfully for the Democratic nomination for Senate in 2016.

Also running are Malcolm Kenyatta, a second-term member of the state House of Representatives from Philadelphia; Val Arkoosh, a former chair of anesthesiology at Drexel University College of Medicine who chairs the three-member board of commissioners in Montgomery County; and Conor Lamb, a third-term member of Congress from suburban Pittsburgh.