"Hillary's health is good," Biden told Clinton workers during a stop at her new campaign office in Charlotte, N.C., according to a reporter traveling with the vice president.

ADVERTISEMENT "I've had pneumonia. I don't know about any of you. I've had walking pneumonia. What you do, you take antibiotics and you rest a little bit," Biden said. "And she's been transparent about her health. ... So we're in good shape. And I'm encouraging her — if the doctor says take three days off, take six days off," Biden said.

Reporters and David Axelrod, a former White House senior adviser to President Obama, criticized the Clinton campaign for not being more open about Clinton's well-being over the weekend. Clinton aides acknowledged Monday they could have done better.

Clinton's campaign said Monday that the candidate would likely appear on the trail again starting later this week after she was forced to leave a 9/11 memorial ceremony early on Sunday.

Her physician said in a statement that evening that Clinton had been battling pneumonia for two days and was overheated and dehydrated at the event.