U.S. Democratic presidential candidate Hillary Clinton leaves ceremonies marking the 15th anniversary of the Sept. 11 attacks at the National 9/11 Memorial in New York, Sept. 11, 2016. Brian Snyder/Reuters

Democratic presidential nominee Hillary Clinton plans to resume campaigning Thursday, spokesman Nick Merrill said Tuesday.

Clinton was forced to suspend her campaign Sunday to recover from a bout with pneumonia. She cut short her appearance Sunday at the Sept. 11 commemorative ceremony in New York, complaining of feeling overheatedand was helped to her van where she appeared to collapse. She then canceled a planned trip to California.

The former secretary of state is scheduled to speak at the Hispanic Caucus Institute gala Thursday, the Los Angeles Times reported.

As Clinton recuperated Tuesday, she spent part of the day watching President Barack Obama campaigning for her in Philadelphia.

“You want to debate who’s more fit to be our President?” Obama asked. “One candidate, who’s traveled to more countries than any secretary of state ever has, has more qualifications than pretty much anyone who’s ever run for this job; and the other, who isn’t fit in any way, shape or form to represent this country abroad and be its commander in chief.”

Clinton has been roundly criticized for not revealing she had pneumonia after it was diagnosed Friday. Her campaign only revealed it after Sunday’s incident.

“I just didn’t think it was going to be that big a deal,” Clinton said Monday in a CNN interview.

Critics, however, said the position points up her penchant for secrecy. Former Obama adviser and political strategist David Axelrod called Clinton’s determination to keep some things private just creates unnecessary problems.

Axelrod, the director of the University of Chicago Institute of Politics, helped mastermind Obama’s victory over Clinton in the 2008 primaries and supports Clinton’s 2016 campaign. But that hasn’t stopped him from taking some jabs. In July he said Clinton looks like a bobblehead when she nods her head to agree with someone.

Clinton’s Republican rival, Donald Trump, had been trying to make an issue of Clinton’s health before Sunday’s incident, saying she didn’t have the stamina to be president. After her near collapse, however, he said only that he hoped she would recover. He pledged to release the results of his latest physical on “The Dr. Oz Show” Thursday.

Clinton’s doctor has said the candidate takes blood thinners and has a thyroid condition. The Clinton campaign said Tuesday more medical information would be released soon.

Trump was to unveil several policy proposals Tuesday at an event in Aston, Pennsylvania, including a child-care tax policy influenced by daughter Ivanka and a guarantee of six weeks of paid maternity leave — a policy at odds with traditional Republican orthodoxy, the Washington Post reported.

Clinton has proposed 12 weeks of paid family leave.