Beto O'Rourke told reporters Saturday that he has no concerns about Sen. Bernie Sanders's fitness for the presidency following the Vermont senator's brief hospitalization for a heart attack last week.

"There isn't a more important voice out there on some of the most important issues that this country faces," said O'Rourke, a former Texas congressman and current 2020 Democratic presidential candidate. "There isn't a more energized, energetic candidate and campaigner keeping up a relentless schedule."

"I have no fears about Bernie Sanders, and [it] does not cause me any concern at all," O'Rourke added, referring to Sanders's hospitalization. "And really all I wish for him is a full and speedy recovery, and his ability to get back after it on the campaign trail. Grateful that he's a candidate and grateful to be in this race with him."

David Sirota, Sanders's speechwriter, applauded O'Rourke's remarks, which came as the Sanders campaign is pushing back against an emerging media narrative that the senator was not forthright about his health scare.

"A class act," tweeted Sirota.

Sanders was discharged from the hospital Friday after two and a half days. On Tuesday, the campaign said Sanders had a heart stent procedure after the senator experienced chest discomfort on the trail in Nevada.

Upon Sanders's exit from the hospital Friday, the campaign released a statement from the senator's doctors announcing he was treated for a myocardial infarction, the medical term for a heart attack.

Responding to criticism of the way the campaign handled Sanders's hospitalization and diagnosis, Mike Casca, senior communications adviser for Sanders, tweeted: "Give me a break. We consistently updated the press and supporters on the senator's condition during his stay through statements and a gaggle with Jane, and we released all the information from his doctors as he was discharged."

In a video posted on Twitter hours after leaving the hospital, Sanders expressed gratitude for the love and well-wishes he received and said he is "feeling so much better."

"See you soon on the campaign trail," Sanders said.