John Fetterman, the Democratic candidate for US Senate in Pennsylvania, said he would not debate Mehmet Oz next week, after the Republican’s campaign mocked his health again.

“Dr Oz’s team … think it is funny to mock a stroke survivor,” Fetterman said.

Fetterman suffered a stroke in May and returned to the campaign trail this month. He leads Oz by about nine points in polls.

Oz, a heart surgeon, made his name as a TV doctor (who admitted in Senate testimony to promoting diet pills which “don’t have the scientific muster to present as fact”). His campaign has chosen to question Fetterman’s health. On Tuesday, it invited the Democrat to a debate next week.

The campaign said: “Dr Oz promises not to intentionally hurt John’s feelings at any point. We will allow John to have all of his notes in front of him along with an earpiece so you can have the answers given to him by his staff in real time.

“At any point John Fetterman can raise his hand and say bathroom break … We will pay for any additional medical personnel who might need to have on standby.”

Fetterman said: “As I recover from this stroke and improve my auditory processing and speech, I look forward to continuing to meet with the people of Pennsylvania.

“Today’s statement from Dr Oz’s team made it abundantly clear that they think it is funny to mock a stroke survivor. My recovery may be a joke to Dr Oz and his team, but it’s real for me.”

Fetterman also said he was “proud of my record as mayor [of Braddock] and as lieutenant governor and I’m eager to put my record and my values up against Dr Oz’s any day of the week”.

He looked forward, he said, to “a productive discussion about how we can move forward and have a real conversation [about debates] once Dr Oz and his team are ready to take this seriously”.

Oz distanced himself from the debate invite, telling KDKA, a Pittsburgh radio station: “The campaign has been saying lots of things.

“My position – and I can only speak to what I’m saying – is that John Fetterman should be allowed to recover fully and I will support his ability, as someone who’s gone through a difficult time, to get ready.”

Oz’s campaign has indeed been saying lots of things.

Last week, responding to Fetterman’s mockery of a video in which Oz complained about the price of crudités, a senior adviser said: “If John Fetterman had ever eaten a vegetable in his life, then maybe he wouldn’t have had a major stroke and wouldn’t be in the position of having to lie about it constantly.”

Fetterman said: “I had a stroke. I survived it. I know politics can be nasty, but even then, I could never imagine ridiculing someone for their health challenges.”