But on Tuesday, Sanders argued that the records he’d released were “quite as much as any other candidate.”

“They think I’m not in good health, come on out with me on the campaign trail. And I’ll let you introduce me to the three or four rallies a day we do. How’s that?” he asked moderator Anderson Cooper, who then sought to clarify that Sanders was declining to release more records. “I don’t think we will, no,” Sanders responded.

Bloomberg was drawn into the clash when Sanders’ national press secretary, Briahna Gray, falsely suggested in an interview with CNN on Wednesday morning that the former mayor had suffered multiple heart attacks. She also compared questions about Sanders’ age and health to the racist birther movement that questioned former President Barack Obama’s citizenship and eligibility for office.

“What you're seeing right now is reminiscent of some of the kind of smear, kind of skepticism campaigns that have been run against a lot of different candidates in the past,” she said. “Questioning where they’re from, aspects of their lineage, etc., etc. It’s telling given that none of the same concern is being demonstrated for Michael Bloomberg, who is the same age as Bernie Sanders, who has suffered heart attacks in the past.”

Kevin Sheekey, Bloomberg’s campaign manager, blasted Gray for “spreading lies” about his candidate while also slamming Sanders over his reluctance to be more transparent about his health.

“This morning, his campaign is spreading an absolute lie that Mike had heart attacks. It's completely false,” he said in a statement.

“The truth is: After a positive stress test in his doctor’s office at Johns Hopkins University in 2000, Mike had two coronary stents placed,” Sheekey continued, contrasting the Sanders team’s slow disclosure with Bloomberg’s. “He quickly told the FAA, consistent with the rules for any pilot, and this information has been public for years. The Bloomberg 2020 campaign released more information about his outstanding health soon after he entered the race.”

Sanders, meanwhile, “had a medical incident in Las Vegas. He didn’t tell the public for days and the full details have never been released,” Sheekey argued. “Facts matter. This isn’t the way to defeat Donald Trump in November.”

Gray later issued a mea culpa, writing in a tweet that she had misspoken when asserting Bloomberg had suffered heart attacks.

“Rather, he underwent the same stent procedure as Bernie,” reiterating her original argument that the records Sanders had released were in line with historical precedent.

While presidential candidates are not required to release any medical records, Sanders himself said prior to his heart attack that releasing medical records is “the right thing to do.”

“The American people have a right to know whether the person they’re going to be voting for for president is healthy,” he said last September.

The concerns about Sanders’ health are part of lingering worries about the ages of this year's White House aspirants, a group that includes four septuagenarians. President Donald Trump, who was 70 when he was inaugurated, is the oldest to assume the office, and has faced intense scrutiny over his medical history.