A battleground Senate race is unfolding in Pennsylvania, one that could ultimately determine which party holds control of the Senate.

The challengers, three-term incumbent Democrat U.S. Senator Bob Casey and his GOP challenger Dave McCormick, went head-to-head in a debate for the first time Thursday.

It's an expensive race for a swing-state seat.

Casey is, perhaps, Pennsylvania's most-well known politician. He's a former state auditor general and treasurer.

He's a staunch ally of labor unions. He originally ran as a pro-life Democrat.

McCormick is making his second run for the Senate after narrowly losing to Dr. Mehmet Oz in 2022's Republican primary.

He's a former hedge fund CEO who served under President George W. Bush's administration, and a West Point grad.

The two went head-to-head in Harrisburg, getting grilled on many of the same topics as the vice presidential candidates just a few days ago.

The first question was on the recent Iran missile attack on Israel.

Casey says the country has to stand with Israel and provide resources and he wouldn't support putting U.S. troops on the ground unless there was a declaration of war.

McCormick says he wouldn't send U.S. troops in to help right now but agreed the U.S. should stand with Israel.

That topic was followed by questions about immigration, the economy, and women's reproductive health.

There are a number of ads targeting McCormick's past statements about abortion restrictions.

McCormick says it's up to each individual state to decide its abortion laws. He accused Casey, who ran as a pro-life Democrat, of flip flopping on his own stance.

"In 2022, when the Supreme Court overturned Roe v. Wade everyone had to make a decision. I made a decision to support the Women's Health Protection Act. I don't support Republicans' efforts to ban abortion across the country," Casey said.

"I think it's important voters decide. They have different preferences, different desires, so that's why I say state rights. In addition to that, I think we should talk more expansively about reproductive rights. One of the things I proposed is an IVF tax credit," McCormick said.

McCormick accused Casey of being weak and blindly following Biden administration policies on the border, the economy, energy, and national security.

Casey, meantime, continued to portray McCormick as a ritzy carpetbagger from Connecticut making money at the expense of others.

"I am taking on corporate greed. I want to pass a price gouging bill. I want to roll back those big corporate tax breaks. He is defending them," Casey said.

"Listen, he's anti-business. He's anti-success. I've had a successful business career. I've served our country in Iraq in combat. He's weak and too liberal," McCormick said.

This was the first but not the last debate between Casey and McCormick. They've agreed to a second on Oct. 15 in Philadelphia.