WATCH: John Fetterman addresses concerns over mental health: 'I'm absolutely sit to serve'

On Thursday, Democratic Pennsylvania Senate candidate John Fetterman sat down with CBS News' Robert Costa to defend himself ahead of next week's midterm elections.

Fetterman, who used a closed captioning device during the interview, was pressed on his mental health, which has gotten to a point where many have suggested that he is no longer fit to serve as a politician.

"Some voters we've spoken to in recent days say they still have some doubts about your health," Costa pointed out. "What would you say to them to convince them otherwise?" 

"I would say we have shown more and shared more kinds of medical evaluation," Fetterman replied, "more than virtually anyone unless you're running for the president."

"I've been campaigning all across Pennsylvania," he continued, "been in front of thousands and thousands of people, and we've been trying to be very very transparent."

Fetterman noted that he and his campaign knew beforehand that the debate with Dr. Oz "was going to be a challenge, given somebody that's in recovery after having a stroke," adding that the journey has been hard not only on him, but his family as well.

"I'm sitting within a chair with you right now to have this conversation," he told Costa, "and really just address the fact that I'm absolutely sit to serve."

Many, however, have suggested otherwise, arguing that Fetterman is in no state to be running for office. 

Following the debate between Fetterman and Oz, Joe Rogan said of the former that he was "clearly compromised to the point where while he's communicating, he's not just stumbling, he's kind of lost in thought and can't form a coherent sentence."

"Why did they think they could put him out there on a huge stage like that?" Rogan asked, adding, "This is not against the guy. I don't know anything about this guy. I really don't. I just know he's the Democratic candidate. But what you're seeing is a guy that has a problem with his brain. That guy should be rehabilitating. He shouldn't be forced into a high-stress job in a public display... It's humiliating." 

Recent polls show Oz and Fetterman neck and neck, making it unclear whether his mental health, which has been the focal point for commentators and pundits, is as much of an issue for voters.