The 60-minute debate was moderated by Action News anchors Matt O'Donnell and Sharrie Williams, along with Univision 65's Ilia Garcia.
It was Casey and McCormick's second debate in two weeks as voting by mail ramps up in Pennsylvania and tens of millions of dollars pour into the swing state race every week. Control of the Senate is on the line, and the race is on track to be the nation's second most expensive in this year's election.
They continued the themes from their combative first debate: McCormick accusing Casey of being a weak, do-nothing, out-of-touch career politician and Casey accusing McCormick of being a wealthy, carpetbagging, ex-hedge fund CEO who got rich at the expense of Americans.
"If he's going to talk about his record versus my record, his record is as a hedge fund CEO investing in China and our adversaries," Casey said. "That's his record. Mine is bipartisan work in the Senate."
McCormick at one point shot back that he wouldn't take any "preaching" from Casey, saying he went into Iraq with the Army in the Gulf War "in the first wave when it looked like there would be tens of thousands of casualties."
McCormick also accused Casey of telling "lies which are completely unworthy of you and your family and your service."
Casey replied, "This isn't a race about his service or what we were doing at that age in our life. It's about my work in the U.S. Senate and his work as a hedge fund CEO."
In a question about U.S. support for Israel amid a widening war in the Middle East, the candidates actually agreed, saying the U.S. must continue its support of Israel and that Israel - not the U.S. - is in the best position to decide how to confront its adversaries, such as Iran.
At almost every other point, they disagreed. On abortion, they had to explain discrepancies in their positions.
Casey - a one-time self-described "pro-life Democrat" - voted in favor of the right to an abortion under the Roe v. Wade standard after the U.S. Supreme Court reversed its 1973 landmark decision on abortion rights.
Casey said most Americans believe daughters shouldn't have fewer rights than their mothers.
No senator "has flip-flopped more on this issue," McCormick said.
McCormick, who supported the high court's 2022 decision to end federal protection of abortion rights, tried to moderate his opposition to abortion rights.
Now, he said, voters - not courts - get to decide whether a state will protect the right to an abortion, even if it means some women don't have that right, and he reiterated that he wouldn't vote for a federal ban on abortion.
On clean energy policy, Casey said billions of dollars from President Joe Biden's 2021 infrastructure law is accelerating the country's clean energy economy and creating jobs. McCormick said it is making the U.S. more reliant on Chinese technology, instead of exporting American natural gas to encourage countries to shut down coal-fired power plants that emit more planet-warming greenhouse gases.
On the filibuster, which requires 60 out of 100 senators to advance legislation in the Senate, McCormick said he supports it because it prevents extreme bills from passing. Casey said it is preventing the passage of popular legislation, including expanding background checks on gun purchases.
"We can do so much to move the country forward, but he wants to hide behind that rule," Casey said.
McCormick, meanwhile, pushed back on stronger gun regulations, saying most gun violence crimes are committed with illegal guns and that restricting gun ownership won't solve it.
Casey, 64, is a former state auditor general and treasurer and is Pennsylvania's longest-serving Democrat in the Senate. He is seeking a fourth term in what he calls his toughest reelection challenge yet.
McCormick, 59, is making his second run for the Senate after losing narrowly to Dr. Mehmet Oz in 2022's Republican primary. He was CEO of Bridgewater Associates, the world's largest hedge fund, sat on former President Donald Trump's Defense Advisory Board and served in top positions under President George W. Bush.
Democrats currently hold a Senate majority by the narrowest of margins but face a difficult 2024 Senate map.