Sen. Bernie Sanders (I-Vt.) suffered a heart attack on Wednesday, Oct. 3,  with his campaign confirming on Friday after he was discharged from Desert Springs Hospital Medical Center in Las Vegas. The sudden medical problem has added uncertainty to Sanders’s 2020 race for president.

The septuagenarian senator from Vermont reportedly experienced “chest discomfort” at a Tuesday campaign event, according to senior adviser Jeff Weaver, wrote an CNN article.

Weaver also said on Wednesday that Sanders will be “canceling his events and appearances until further notice.” On Thursday, his campaign confirmed that he will be participating in the next Democratic primary debate on Oct. 15 and that he plans to return to Vermont in the coming days before partaking in the debate, CNN reports.

Sanders and his campaign are rushing to contain the cloud of uncertainty that has settled over his candidacy, Politico reported. According to interviews with Sanders’s aides and surrogates, they’re betting that his performance at next week’s debate and on the campaign trail will determine whether he has the stamina to continue his pursuit of the presidency.

Andres Ramirez from Nevada, a Democratic strategist and former vice chairman of the Democratic National Committee’s Hispanic Caucus, noted that it would be dangerous if Sanders’s campaign is not transparent with his health issue.

“It’s one of those things where the cover-up is worse than the crime,” Ramirez said. “I don’t think anybody would have cared if they said he had a heart attack, got out a few days later, and then everything’s good.”

Instead, he said, “There seemed to be a refusal or hesitance to say, ‘Bernie Sanders had a heart attack.’ …I think it’s less of an issue about his age and more of an issue of, ‘Hey, Bernie, you’re supposed to be the transparent candidate.’”

CNN’s Chris Cillizza analyzed that, Sanders is not the only Democratic presidential candidate affected by the news of his heart attack, pointing out that the former Vice President Joe Biden and Sen. Elizabeth Warren (D-Mass.) are 76 and 70, respectively.

“While Sanders and his campaign [and his supporters] are quick to downplay how serious [or not] this heart attack was for the Vermont senator, it’s hard to get away from this fact: Sanders, a 78-year-old man, had a heart attack that required surgery,” Cillizza wrote. “While there are lots and lots of people who have this exact experience, most of them are not running for president. And no one disputes that being president—or even running for it—is a hugely stressful job.”

Cillizza pointed out that the public appears to have mixed feelings about older candidates running for president, citing a May Pew Research Center poll that just 3 percent of Democrats said their ideal candidate would be in their 70s. On the other hand, a higher percentage—71 percent—said they would vote for a candidate under the age of 40.

Sanders’s campaign has yet to notify the public the severity of his heart attack.