Ms. Shalala, in an interview on Thursday, acknowledged the difficulties. “Last year was a tough year,” she said, “because people were beating on us with nonsense,” a reference to bruising political attacks claiming that donors were using the foundation to curry favor with the Clintons.

Image “Last year was a tough year,” said Donna E. Shalala, president of the Clinton Foundation, whose tenure is in question. Credit... Rodrigo Varela/Getty Images

Revenues were down for 2016, Ms. Shalala acknowledged, in part because of voluntary restrictions and the fact that the charity’s major fund-raisers — the former president and his daughter, Chelsea — were campaigning for Mrs. Clinton. Revenues “dropped during the economic downturn, too,” Ms. Shalala said.

Still, both Mr. Clinton and Ms. Shalala, who also cited concerns in keeping talent, expressed optimism. “At the end of the day,” she said, “I think this is going to be as it always was: a creative, dynamic foundation that helps to improve the lives of millions.”

As the foundation looks within, many experts said it was right to assess its future, including whether a great enough need still existed for its most prominent asset: the ability to bring the private sector together with charities to help underserved causes.

“It’s certainly a different landscape than it was” when the foundation’s work began, said Carolyn Miles, president and chief executive of Save the Children, one of the foundation’s early partners. “I would say you have to come back as something slightly different.”