HARRISBURG, Pa. — Sen. Bob Casey raised eyebrows debating GOP challenger Dave McCormick Thursday night when the Scranton native refused to say which Democrat would be better for Pennsylvania — Vice President Kamala Harris or former candidate President Biden.

Casey initially dodged ABC27 moderator Dennis Owens’ question, then visibly bit his lip before responding when pressed.

“Oh, I don’t know, Dennis. We’ll never know the answer to that,” the Democrat said. “The voters are going to make a decision.”

Of course, the decision of the nearly 14.5 million Americans who voted for Biden — another Scranton native — in this year’s Democratic primaries was thrown out the window.

The Casey-McCormick face-off in Harrisburg was the first of three planned debates in the tight race; they’ve agreed to meet again in Philadelphia Oct. 15 and Pittsburgh on an unspecified date.

McCormick attempted to paint Casey as “weak” and “liberal” in their first matchup, tying the senator’s voting record to Biden and Harris while repeatedly touting his campaign’s opposition website about the incumbent, CaseyLies.com.

“You should ask yourself: Why is a senator with an 18-year track record who should be able to run on his record running his entire campaign with a negative set of attacks on me, most of them lies?” McCormick said.

Casey largely focused his attacks on McCormick’s past residence in Connecticut while CEO of the hedge fund Bridgewater Associates.

When Casey cited an August 2023 AP article alleging McCormick lied about his Pennsylvania residency, the businessman fired back fiercely.

“The fact that he got some reporter at the Associated Press to validate his lies or reinforce his lies does not mean it’s true,” the Republican replied.

McCormick moved back to Pittsburgh’s Squirrel Hill neighborhood in 2022 to run for Senate but grew up in Bloomsburg.

Both men accused each other of not standing up to their party’s more “extreme” factions, particularly on border security.

McCormick — who has visited the US-Mexico border twice — slammed Casey for neglecting to go at all.

“Senator, you speak a lot about the border. I suggest you go,” McCormick said. “I’ve been to the border more times than the senator and the border czar.”

“I guess Mr. McCormick knows more about border security than the Border Patrol. I don’t think so,” Casey retorted.

Casey also went after McCormick for not standing up to former President Donald Trump when he persuaded Senate Republicans to kill a bipartisan border bill.

“Leadership would be taking on the leader of your own party and supporting the bill,” Casey said.

McCormick was not serving in government when GOP senators killed the bill earlier this year.

At an Americans for Prosperity Action watch party down the road, attendees praised McCormick’s performance.

Bill Gramlich, a 60-year-old self-employed home-improvement contractor, has volunteered with AFP Action in Pennsylvania for the past eight years and canvassed on McCormick’s behalf this year.

Gramlich told The Post this election feels different: McCormick, he said, is a “more viable candidate.” (The controversial Dr. Mehmet Oz lost to Democratic Sen. John Fetterman in 2022.)

“He’s energized, and people are very enthusiastic about him running for this election against Bob Casey,” he said.

“His credentials are really, really good, he’s a top-notch leader,” he added, citing the West Point graduate’s business accomplishments and service as a paratrooper in the 82nd Airborne Division.

AFP PA Senior Adviser Emily Greene said her team of more than 230 canvassers aims to knock on 1 million doors before Election Day — and has already hit more than 750,000 since April.

She said that “no one is feeling prosperity under this current economy,” so they’re looking for change.

“They want something different,” she said. “They want to actually find prosperity, and they’re not doing it through Sen. Bob Casey’s leadership.”