Publisher Health

It began with a spat over crudités. It has escalated into one Senate hopeful who is openly mocking another’s health after a stroke.

Dr. Mehmet Oz, the Republican nominee for Senate in Pennsylvania, has taunted his Democratic rival, Lt. Gov. John Fetterman, about his stroke recovery, suddenly thrusting an issue both candidates had tiptoed around into a central theme of one of the most watched races of the year.

Mr. Fetterman said on Tuesday that he would not participate in a debate in early September, implying that his recovery from his stroke in May was not complete enough for him to perform at the peak of his abilities. His decision came after a day of goading by the Oz campaign.

“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,” Mr. Fetterman, who returned to campaigning this month, said in a statement.

Earlier in the day, the Oz campaign had issued a list of bogus “concessions” it would make if Mr. Fetterman agreed to a Sept. 6 debate hosted by Pittsburgh’s KDKA-TV, including “We will pay for any additional medical personnel he might need to have on standby” and “At any point, John Fetterman can raise his hand and say, ‘Bathroom break!’”

The ugly turn in the race, whose outcome could help determine which party controls the Senate after the fall elections, opened Dr. Oz, who left a career as a heart surgeon and TV celebrity to run for office, to accusations of resorting to low blows. While there is a long tradition in American politics of candidates’ questioning rivals’ health and fitness for office, Dr. Oz seized on the issue as he has been reviving his struggling candidacy.

The attacks have pried open an issue that the Fetterman campaign has sought to control — Mr. Fetterman’s health — by avoiding free-for-all questioning from the news media or voters since the candidate’s return to campaigning this month.

After suffering a stroke days before the primary, Mr. Fetterman had a pacemaker and defibrillator implanted. His campaign at first released little information. Eventually, it disclosed he had been diagnosed with a heart condition, cardiomyopathy, which makes it harder for the heart to pump blood to the body. In a statement at the time, Mr. Fetterman’s doctor said he should be able to campaign and serve in the Senate without problems if he takes his recovery “very seriously.”

Before returning to the campaign trail on Aug. 12, Mr. Fetterman acknowledged he sometimes dropped or slurred words but was improving daily.

At an Aug. 23 appearance in Pittsburgh, his speech was halting, and he sometimes searched perceptibly for the right words. Conservative news outlets and commentators seized on clips from the appearance to portray Mr. Fetterman as unfit.

For months during his convalescence, the Fetterman campaign consisted largely of insulting Dr. Oz on social media, including calling him a carpetbagger from New Jersey. That effort paid off with millions of online interactions and a flood of donations.

Then, when Mr. Fetterman made fun of Dr. Oz for a resurfaced video in which Dr. Oz was shopping for what he called “crudités” in the vegetable aisle, to demonstrate the impact of inflation, the Oz campaign returned fire in a different way.

“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,” an Oz spokeswoman, Rachel Tripp, said in a statement.

The Oz campaign continued to bring up the issue of Mr. Fetterman’s health to attack him for not committing to a series of five debates. Dr. Oz insinuated that his opponent was shirking a confrontation.

Asked in a radio interview Tuesday whether his campaign went too far in attacking Mr. Fetterman for causing his stroke by skipping vegetables, Dr. Oz struck what seemed like false solicitude: “John Fetterman should be allowed to recover fully, and I will support his ability as someone going through a difficult time to get ready.” Later in the day, the Oz campaign embraced an openly sarcastic tone when it released its list of debate “concessions.”

Mr. Fetterman reacted strongly. “Today’s statement from Dr. Oz’s team made it abundantly clear that they think it is funny to mock a stroke survivor,” Mr. Fetterman said in a statement. “I chose not to participate in this farce.”

“My recovery may be a joke to Dr. Oz and his team, but it’s real for me,” he added.

Democratic strategists in Pennsylvania not affiliated with the Fetterman campaign said that questions about his health or appearance in debates were unlikely to shake his support, which two recent polls put at an edge of four or five percentage points over his rival.

“As a Democrat, I would rather have Oz talking about debates — an issue that few voters care about — than talking about inflation,” said J.J. Balaban, a Democratic strategist. “And Fetterman’s stroke was widely reported, so voters’ concerns may already be baked in the cake.”

Many Republican base voters have been slow to coalesce behind Dr. Oz because of suspicions that he is neither a true conservative nor a member of the Make America Great Again movement. Seeing influential conservatives take up the issue of Mr. Fetterman’s health — including the Fox News host Laura Ingraham and the commentator Ben Shapiro — may help secure those Republicans’ support for Dr. Oz.

However, there is also the potential for backlash against Dr. Oz. On Wednesday, Mr. Fetterman released a video in which he asks a roomful of voters, “How many of you have had a big health challenge in your life?”

“Can you even imagine that if you had a doctor that was mocking your illness or ridiculing that?” he added. “Well, here we are.”