Harris used to worry about laughing. Now joy is fueling her campaign.

The crowds during a rally Wednesday in Philadelphia for Vice President Kamala Harris and her running mate, Gov. Tim Walz of Minnesota. (Erin Schaff/The New York Times)

A Kamala Harris pin seen at the Vice President’s rally Wednesday in Romulus, Mich. (Erin Schaff/The New York Times)

WASHINGTON — There was a time, early in her vice presidency, when Kamala Harris, aware of reams of conservative news coverage criticizing her laughter, privately wondered to confidants whether she should laugh, or show a sense of humor, at all.