Fetterman, the state’s Democratic lieutenant governor, and Republican Oz, who shot to fame as a TV doctor, are vying for a crucial Pennsylvania seat that could decide the balance of power in the Senate.

Fetterman, who suffered a stroke more than five months ago, struggled to communicate effectively at times, missing some words and speaking haltingly. He used closed-captioning posted above the moderator to help him process the moderator’s questions and Oz’s responses, leading to some awkward pauses.

Those speech challenges were apparent throughout the night, but a particularly painful moment came when he was asked to explain his shifting position on fracking, a method of natural gas production that employs tens of thousands of people in Pennsylvania.

“I do support fracking. And I don’t, I don’t. I support fracking, and I stand and I do support fracking,” Fetterman said.

He previously backed a moratorium on new fracking in his unsuccessful 2016 Senate bid.

Fetterman addressed his health in the debate’s opening minutes, referring to it as the “elephant in the room.”

“I had a stroke. He’s never let me forget that,” he said of Oz, who has repeatedly questioned his opponent’s ability to serve in the Senate. “And I might miss some words during this debate, mush two words together, but it knocked me down and I’m going to keep coming back up.”

He later refused to commit to releasing his full health records when asked by the moderator. “My doctor believes that I’m fit to serve,” he said.

Some took to Twitter to say the debate was disastrous for Fetterman and could cost him the race.

“Tragically, after tonight’s disastrous debate performance by John Fetterman, Dr. Oz, who is a huckster and a scumbag, is going to win that Senate race, which will probably flip the Senate for the Rs,” tweeted The Hollywood Reporter’s Scott Feinberg. “I feel sorry for Fetterman and for all of us who will be stuck with the fallout.”

Journalist Aaron Rupar noted that the fracking question “was a tough moment for Fetterman.”

Sean Trende, a political analyst, wrote: “Look, it sounds like the debate is an utter disaster for him. But few will watch it, and it’s a hard thing to go on the attack about without inspiring a backlash. This hurts Fetterman, but I don’t think things have shifted all that dramatically.”

However, others defended Fetterman, and some praised him for agreeing to the debate.

Writer and journalist Connie Schultz wrote: “My God, the blue-check people here mocking John Fetterman during this debate, as if they are immune from the randomness of illness and infirmity. Time catches up with everyone, no exceptions. Few would have his courage to recover so publicly.”

Ana Navarro-Cárdenas said Fetterman “could’ve refused to debate like some candidates have. Instead, he went out there and let voters see his challenges and healing process. Support him or not, that takes courage, humility and honesty.”

SiriusXM host Dean Obeidallah wrote that Fetterman’s cognitive skills “will improve over time. Dr. Oz will ALWAYS remain a Trump loving, serial liar who tried to con people into using BS medical treatments. The voters of Pennsylvania rejected a conman in 2020 when they said no to Trump, they will do it again in 2022.”

Laura Bassett, the editor-in-chief of Jezebel, added: “Everybody tweeting about the Oz / Fetterman debate like we’re talking about two similarly legitimate candidates. Is everyone insane? Fetterman has been working (successfully) in public service in Pennsylvania for a decade. Oz is a quack TV doctor!”

For much of this year, Fetterman seemed the clear favorite to win, but the race has tightened as Election Day nears. Fetterman is now leading just slightly in the race, according to averages of recent polls compiled by RealClearPolitics and FiveThirtyEight.

Fetterman and Oz’s campaigns have been contacted for comment.