Hillary Clinton returns to the campaign trail in Greensboro, N.C., on Thursday. (Photo by Melina Mara/The Washington Post)

GREENSBORO, N.C. — Rejoining her campaign on Thursday, Hillary Clinton twice declined to say whether her running mate, Sen. Tim Kaine (D-Va.), knew about her pneumonia when she was diagnosed last week.

The Democratic presidential nominee  was back on the trail after taking a three-day break to rest. Asked during a news conference about when Kaine was informed of her illness, she gave no details.

"My senior staff knew, and information was provided to a number of people," Clinton said in response to the first question. She also repeated that she would be able to work through the sickness after being diagnosed on Friday.

On Sunday, Clinton attended a commemorative ceremony for the 9/11 attacks at Ground Zero in New York and became unsteady, leaving the event early. Her campaign later revealed that the candidate was suffering from mild pneumonia.

"I don’t want to stop," Clinton said Thursday in North Carolina. "I didn’t want to quit campaigning. I  certainly didn’t want to miss the 9/11 memorial. As a senator [from New York] at the time, I consider it a sacred moment. I was determined to be there."

On Sunday, Kaine indicated that he had spoken to Clinton about her illness, but he would not say if she had told him about it the day she was diagnosed.

Asked by a second reporter in North Carolina on Thursday, Clinton again declined to discuss the conversations she had with Kaine. "I communicated with Tim; I talked to him again last night," Clinton said. "We communicated, but I’m not going to go into our personal conversations."