Democrat Sen. Bob Casey of Pennsylvania and Republican challenger Dave McCormick face off Tuesday in their second and final debate.

The showdown in the key battleground state comes with three weeks to go until Election Day in a crucial, combustible and expensive Senate showdown that may decide whether the GOP wins back the chamber’s majority.

And if the face-off is anything like their first debate, which quickly became personal as both candidates accused their opponent of lying, expect more verbal fireworks.

Casey, during the first debate, argued that McCormick, a former hedge fund executive, West Point graduate, Gulf War combat veteran and Treasury Department official in former President George W. Bush’s administration, is a wealthy carpetbagger.

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McCormick, who grew up in northeast Pennsylvania and who is the son of the Keystone State’s first state university system chancellor, has come under attack in both his 2022 and 2024 Senate runs for owning a house in an affluent part of Connecticut during his tenure as CEO of Bridgewater Associates. 

The narrator in a Casey digital ad that launched on the eve of the final debate charges that McCormick “told voters he lived in Pennsylvania when he was really living in Connecticut. Hope he can find his way back.”

And on the campaign trail this past weekend, referring to McCormick, Casey argued that “you shouldn’t lie to the people you seek to represent, especially about something as simple as where you live.”

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McCormick, in a Fox News Digital interview last week in Pittsburgh, said he’s “a seventh-generation Pennsylvanian.”

During their first debate, McCormick targeted Casey as a do-nothing career politician.

Casey, the son of a popular former governor, is running for a fourth six-year term in the Senate. He served a decade as Pennsylvania’s auditor general and then treasurer before winning election to the Senate in 2006.

“With Bob Casey, you have a guy who’s a career politician, 30 years in elected office, who has shown he won’t lead and who has voted 99% of the time with Biden-Harris and will vote 99% of the time with Harris-Walz,” McCormick said in his interview.

McCormick said he’s “a business guy, someone who went to West Point, somebody who’s a combat vet. That kind of independence and leadership is what’s seriously lacking in Pennsylvania.”

Pointing to polls that indicate Casey’s lead shrinking, McCormick said that “what you have here is a career politician, 30 years in elective office, who’s fighting for his life. He, all of a sudden, is waking up and the possibility of losing is really dawning on him.”

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McCormick was part of a crowded and combustible battle for the 2022 GOP nomination. He ended up losing the nomination by a razor-thin margin to celebrity doctor and cardiac surgeon Mehmet Oz, who secured a primary victory thanks to a late endorsement from former President Trump. Oz ended up losing the general election to then-Democrat Lt. Gov. John Fetterman.

This time around, McCormick faced no major opposition in the GOP primary. He was backed last year by longtime Senate Republican leader Mitch McConnell as well as the Pennsylvania GOP, and he was encouraged to run by the National Republican Senatorial Committee, which is the party’s Senate campaign arm.

And Trump endorsed McCormick in March. Since then, the Senate GOP nominee has rarely missed an opportunity to appear with Trump during the former president’s numerous rallies in Pennsylvania, which is the largest of the seven key presidential battleground states.

“For me to win in Pennsylvania, I need to run my own campaign, which I’m doing. But I also need to do two things. I need to be able to turn out the voters across our Republican Party in these red counties … and President Trump’s unbelievably helpful in that. He’s been very supportive of me, and I’ve been supportive of him,” McCormick said.

But he added that “I also need to be able to appeal to independents. I need to be able to appeal to people who are on the fence, places like Alleghany County where we live and places like southeast Pennsylvania, the collar counties around Philadelphia. And I’m able to do that because of the life I’ve led, because the fact that I’ve shown my independence. Sometimes I’ve disagreed with President Trump.”

Get the latest updates from the 2024 campaign trail, exclusive interviews and more at our Fox News Digital election hub.