HARRISBURG, Pa. (AP) — Jake Corman, the ranking Republican in Pennsylvania’s state Senate, will run for governor in next year’s election, a political adviser said Wednesday, entering a huge and wide-open GOP field of candidates that is unlike anything party officials have seen in at least decades.

For weeks, Corman has been expected to enter the race, and he had planned to make the formal announcement at a Thursday night event, a political adviser with direct knowledge of Corman’s plans told The Associated Press.

The political adviser spoke on condition of anonymity because Corman has not publicly confirmed he is running, although Corman has repeatedly hinted that an announcement is coming.

However, the Thursday night event — billed as a “special announcement” in Corman’s hometown of Bellefonte — was canceled after Corman tested positive Wednesday for COVID-19.

He is fully vaccinated and will quarantine at home, the Senate Republican communications office said in a brief statement. Corman’s symptoms are mild, it said, but did not elaborate.

Corman will enter a wide-open race for the GOP nomination, swelling an already big field of Republicans to potentially succeed outgoing Gov. Tom Wolf, a Democrat.

Corman, 57, who represents a swath of central Pennsylvania surrounding Penn State’s main campus, is the Senate’s president pro tempore and has served in the chamber since 1999 after taking over the seat his father held.

On the Democratic side, two-term state Attorney General Josh Shapiro is the presumed nominee and has thus far cleared the primary field, having amassed a campaign account of $10 million and won two statewide races.

After last week’s municipal election, candidates began burning up the phones of county Republican Party chairs, asking for meetings.

The field is double digits deep, something party officials can’t ever remember confronting in a statewide race of such importance.

“I was thinking it was getting close to 20,” said Cambria County GOP chair Jackie Kulback.

The big field is a sign of strength, not weakness, Kulback said, especially considering that a Republican has replaced every outgoing Democratic governor under Pennsylvania’s modern constitution, which allows for two-term governors.

“It’s a sign of opportunity,” Kulback said. “It’s a sign that Republicans have a leg up on Shapiro.”

Candidates will have various tests in front of them to show their strength.

The state party’s regional caucuses will begin holding candidate meetings in January, where members typically take a straw poll after a Saturday of meeting privately with candidates to let the candidates know where they stand.

“For our committee, it’s important to actually meet the candidate and just size them up,” Kulback said. “Like, do they have the personal fortitude to run a statewide campaign? It’s not easy.”

The next state deadline to report campaign finances is Jan. 31, when candidates must show how much money they have raised.

In February, the state party will hold its winter meeting, where state committee members typically try to vote on endorsements in statewide races.

“You’ve got so many candidates at this point in time that I don’t know how it’s going to be sorted out,” said Dick Stewart, who is co-chair of the state party’s central caucus. “I would be surprised if somebody can garner enough votes to get an endorsement from the state committee.”

After that, the deadline for candidates to submit petitions with enough voter signatures to get on the May 17 primary ballot is in March. Getting the required number of signatures shows a candidate’s ability to organize a campaign.

Stewart said the last time the state party had a crowded field for the gubernatorial nomination was in 1978. That year, seven names were on the GOP primary ballot, including Dick Thornburgh and Arlen Specter.