Joseph R. Biden Jr. unfurled sharply personal new lines of attack against Senator Elizabeth Warren on Tuesday, questioning her contributions to the Democratic Party and seeking to cast her as an elitist who believes people lack courage or wisdom unless they agree with her.

“Some call it the ‘my way or the highway’ approach to politics,” Mr. Biden, the former vice president, wrote in a Medium post. “But it’s worse than that. It’s condescending to the millions of Democrats who have a different view. It’s representative of an elitism that working and middle-class people do not share: ‘We know best; you know nothing.’ ‘If you were only as smart as I am you would agree with me.’ This is no way to get anything done.”

Mr. Biden repeated similar arguments in a fund-raising email and at a fund-raiser in Pittsburgh on Tuesday, escalating tensions between the two top-polling contenders for the Democratic presidential nomination. He did not mention his rival by name, but the message was unmistakably aimed at Ms. Warren, whose Republican critics have for years sought to paint her as an out-of-touch liberal who worked as a Harvard professor.