“I know what it is to campaign hard and to work hard,” Mr. Lewis said, acknowledging that he faced some “problems now, but they will not be with me forever.” “And I will be out there working and campaigning for Joe Biden as president of the United States of America.”

Mr. Biden has not yet clinched the Democratic nomination; Senator Bernie Sanders of Vermont continues to campaign too. But with Mr. Biden holding an almost insurmountable lead in delegates, his campaign has started the process of looking for a running mate. He has said he will pick a woman.

Older black voters, in particular, revived Mr. Biden’s once-floundering candidacy and played a decisive role in propelling him to the cusp of the Democratic nomination. Some Democrats — including Representative James E. Clyburn of South Carolina, the highest-ranking African-American in Congress and a top Biden ally — have expressed a preference for a black woman on the ticket with Mr. Biden.

“I think Vice President Biden should look around,” Mr. Lewis said, when asked if he believed Mr. Biden should select a woman of color. “It would be good to have a woman of color. It would be good to have a woman. It would be good to have a woman who looks like the rest of America.”

Mr. Lewis noted that there are “plenty of able women. Black, white, Latino, Asian-American, Native American.” The time has “long passed,” he said, for making “the White House look like the whole of America.”