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.

Ms. Warren is running as a corruption-battling economic populist, and her campaign has emphasized that she grew up in Oklahoma “on the ragged edge of the middle-class.” Her campaign declined to comment on Mr. Biden’s remarks.

MR. RUSSERT: But, senator, we have a deficit. We have Social Security and Medicare looming. The number of people on Social Security and Medicare is now 40 million people. It’s going to be 80 million in 15 years. Would you consider looking at those programs, age of eligibility...

SEN. BIDEN: Absolutely.

MR. RUSSERT: ...cost of living, put it all on the table.

SEN. BIDEN: The answer is absolutely. You have to. You know, it’s—one of the things that my, you know, the political advisers say to me is, “Whoa, don’t touch that third”—look, the American people aren’t stupid. It’s a real simple proposition. We have to do—you and I were talking about Bob Dole earlier. I was one of five people—I was the junior guy in the meeting with Bob Dole and George Mitchell when we put Social Security on the right path for 60 years. I’ll never forget what Bob Dole said. After we reached an agreement about gradually raising the retirement age, etc., he said, “Look, here’s the deal, we all put our foot in the boat one at a time.” And he kicked—he stepped like he was stepping into a boat. “And we all make the following deal. If any one of the challengers running against the incumbent Democrat or Republicans attack us on this point, we’ll all stay together.” That’s the kind of leadership that is needed. Social Security’s not the hard one to solve. Medicare, that is the gorilla in the room, and you’ve got to put all of it on the table.

MR. RUSSERT: Everything.

SEN. BIDEN: Everything. You’ve got to.