FILE - In this Sept. 15, 2021 file photo, state senator Jake Corman (R-Centre), speaks during a Senate Intergovernmental Operations Committee hearing at the Pennsylvania Capitol in Harrisburg, Pa. (AP Photo/Matt Rourke, File) Jake Corman
FILE - In this Sept. 15, 2021 file photo, state senator Jake Corman (R-Centre), speaks during a Senate Intergovernmental Operations Committee hearing at the Pennsylvania Capitol in Harrisburg, Pa. (AP Photo/Matt Rourke, File)

An already crowded GOP field could grow with Senate President Pro Tempore Jake Corman’s expected announcement that he is running for governor.

HARRISBURG — Jake Corman (R-Centre), the ranking Republican in Pennsylvania’s state Senate who is widely expected to run for governor, has begun inviting donors and others to an announcement next Thursday night.

The event is billed as a “special announcement” in Corman’s hometown of Bellefonte.

Corman’s entry into the race would swell an already big field of Republicans running for governor, double-digits deep and growing as the party searches for a nominee to 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.

For weeks, Corman has been expected to enter the race, meeting with donors and the congressional delegation. Corman has said he would discuss his political plans after Tuesday’s election, but neither he nor a political adviser have returned messages about it.

He has served in GOP leadership since 2009 and is well known to party donors as part of his fundraising for himself and the Senate’s majority party.

But his impending candidacy is not clearing the field of Republican rivals. 

On Friday, Charlie Gerow announced he was launching a new cable TV ad campaign and state Sen. Doug Mastriano said he would begin fundraising for a gubernatorial campaign.

On Saturday, Gerow, a Harrisburg-area marketing consultant, and six other gubernatorial hopefuls were expected at a Tioga County Republican Party dinner, while in Delaware County, Dave White, who runs a large plumbing and HVAC firm, is formally announcing his candidacy.

The Republican field includes Lou Barletta, a former four-term member of Congress who was the Republican nominee in his 2018 loss to Democratic US Sen. Bob Casey and has been a prominent loyalist of former President Donald Trump.

Corman’s standing with Trump loyalists is mixed, at best.

Over the summer, Trump and his allies in the baseless quest to prove that Democrats stole the 2020 presidential election had held up Corman as an obstacle, before Corman abruptly embraced it.

“I’m a hundred percent on board with this,” Corman declared in late August, speaking on former Trump adviser Steve Bannon in Bannon’s War Room online broadcast.

Corman also has a long voting record that could be picked apart, including bipartisan measures that aged poorly and have become grist for primary attacks from the right against various Republican lawmakers.

For instance, he voted in 2005 for a broad government pay raise — rammed through without public hearings in the middle of the night — that stirred such a backlash that lawmakers three months later voted to rescind it.

In 2013, he voted along with Republican leaders for an increase in the gas tax and motorist fees to fund highway construction projects, a measure backed by business groups and labor unions. The law makes Pennsylvania’s gas tax the second-highest in the nation.

Then in 2019, he and nearly every other Republican lawmaker voted for sweeping election legislation that, among other things, authorized no-excuse mail-in voting, mere months before the pandemic and before Trump mounted a campaign to tar mail-in voting as rife with fraud.

Many Republicans have since soured on mail-in voting, with candidates on the gubernatorial campaign trail calling for its repeal.

Corman, meanwhile, is a plaintiff in a lawsuit challenging the authority of the Wolf administration to order a school mask mandate. 

On the Democratic side, two-term state Attorney General Josh Shapiro has announced that he will seek the party’s nomination and his candidacy has thus far cleared the field of rivals.

Wolf is constitutionally barred from seeking a third term.