An NBC News correspondent who interviewed the Pennsylvania Senate candidate, Lieutenant Governor John Fetterman, says an on-air remark she made about him having difficulty following part of their conversation should not be seen as a commentary on his fitness for office after he suffered a stroke.

Yet reporter Dasha Burns’ comment that Mr. Fetterman appeared to have trouble understanding small talk prior to their interview has attracted attention — and Republicans have retweeted it as they seek an advantage in the closely followed Senate race between Mr. Fetterman and the Republican, Dr. Mehmet Oz.

Mr. Fetterman, a Democrat, suffered a stroke on May 13, and his health has emerged as a major issue in the campaign.

Ms. Burns’ Friday interview with Mr. Fetterman, which aired Tuesday, was his first on-camera interview since his stroke. He used a closed-captioning device that printed text of Ms. Burns’ questions on a computer screen in front of him.

Mr. Fetterman appeared to have little trouble answering the questions after he read them, although NBC showed him fumbling for the word “empathetic.” Ms. Burns said that when the captioning device was off, “it wasn’t clear he was understanding our conversation.”

“This is just nonsense,” business reporter and podcaster Kara Swisher, who had a stroke herself in 2011, said on Twitter. “Maybe this reporter is just bad at small talk.”

Ms. Swisher recently conducted an interview with Mr. Fetterman for her podcast and said, “I was really quite impressed with how well he’s doing. Everyone can judge for themselves.” Ms. Swisher has called attacks on Mr. Fetterman because of his health “appalling.”

A New York magazine reporter, Rebecca Traister, who interviewed the candidate for a cover story titled “The Vulnerability of John Fetterman,” tweeted that his “comprehension is not at all impaired. He understands everything. It’s just that he reads it and responds in real time … It’s a hearing/auditory challenge.”

Ms. Burns said she understands that different reporters had different experiences with Mr. Fetterman.

“Our reporting did not and should not comment on fitness for office,” Ms. Burns tweeted on Wednesday. “This is for voters to decide. What we push for as reporters is transparency. It’s our job.”

Stories about the interview aired on “NBC Nightly News” and the “Today” show.

Mr. Fetterman, 53, has been silent about releasing medical records or allowing reporters to question his doctors. He’s been receiving speech therapy and released a letter in June from his cardiologist, who said he will be fine and able to serve in the Senate if he eats healthy foods, takes prescribed medication and exercises.

Problems with understanding and using language are common in recovering stroke victims, said the director of the Yale University Center for Brain and Mind Health, Kevin Sheth. Some completely recover, some have continued impairments, he said.

“There is an arc to the trajectory of recovery that varies from person to person,” Mr. Sheth said.

But he cautioned that, without an examination, people should not make judgments about Mr. Fetterman’s condition based on his use of a language-assistance device.

Ms. Burns’ statement about Mr. Fetterman has already been tweeted by political opponents, including the National Republican Senatorial Committee and the Republican National Committee.

The conservative website Townhall.com tweeted Ms. Burns’ quote, without making clear she had been referring to small talk and not the interview itself.

The press secretary for Senator McConnell, Doug Andres, tweeted that it was weird to see liberals attack a reporter for doing her job.

“It’s almost like that whole thing about respecting and trusting the media is only true when it’s convenient for them,” he wrote.