LAS VEGAS — In a storefront on this city’s heavily Latino east side, the civil rights leader Dolores Huerta rallied a dozen volunteers for Hillary Clinton on Wednesday night, relating in Spanish a Mexican saying about people who go near a cactus only when it is bearing fruit.

“Bernie hasn’t been around,” Ms. Huerta said, referring to Senator Bernie Sanders of Vermont, Mrs. Clinton’s opponent in Nevada’s Democratic caucuses on Saturday. “He came to see the Latinos when they had the fruit.”

Fifteen minutes away, the Mexican actor and game-show host Marco Antonio Regil stood in the backyard of a suburban home, urging on volunteers for Mr. Sanders and his vow to fight income inequality.

He recalled growing up in Tijuana, with its wide gap between the rich and the poor. “We cannot allow that extreme social disparity to happen in America,” Mr. Regil said.