The entrepreneur Andrew Yang was struggling in obscurity when, about a year ago, he went on Joe Rogan’s podcast, “The Joe Rogan Experience.”

Almost immediately, the donations started pouring in. Senior members of Mr. Yang’s campaign have said his two-hour interview with Mr. Rogan was responsible for bringing in hundreds of thousands of dollars and significantly raising his profile.

Three months later, Representative Tulsi Gabbard of Hawaii joined the podcast; three months after that, on came Senator Bernie Sanders of Vermont. All of the candidates knew just how huge an audience Mr. Rogan had developed.

This week, Mr. Rogan, the stand-up comedian, mixed martial arts commentator and sometime actor who, through his podcast, has become an unlikely political influencer, said he would throw his support behind Mr. Sanders in the 2020 Democratic primary — an endorsement that could bolster the candidate particularly among the legions of disaffected male voters who have long been critical to his chances to win.