Stacy Garrity, Pennsylvania’s two-term elected state treasurer, said Monday that she will seek the Republican nomination to challenge Democratic Gov. Josh Shapiro ’s reelection bid, setting up what could be a contest between a low-profile officeholder and a potential White House contender in 2028.

Republicans hope Ms. Garrity, the state treasurer, will give them a shot against Gov. Josh Shapiro. But he will be tough to beat, and the Republican field could still be complicated by Doug Mastriano.

State GOP leaders are expected to throw their support behind Garrity. Many of them are worried about a second run from state Sen. Doug Mastriano.