“Run, Liz, run!” the crowd chanted as the senator took the stage for her morning talk. Ms. Warren tried to shush them, waving her arms and admonishing them like the teacher she once was: “Sit down, people. Come on, let’s get started.” Then she opened with the sort of blistering populist assault on corporations, Republicans, banks, lobbyists and trade deals that has become her trademark.

“They cheated American families, crashed the economy, got bailed out, and now the biggest banks are even bigger than they were when they got too big to fail in 2008!” Ms. Warren thundered, in one of her many applause lines. “A kid gets caught with a few ounces of pot and goes to jail, but a big bank launders drug money and no one gets arrested. The game is rigged!”

She went on: “Billionaires pay taxes at lower rates than their secretaries. How does this happen? It happens because they all have lobbyists. Lobbyist and Republican friends in Congress. Lobbyists and Republicans to protect every loophole and every privilege. The game is rigged, and it isn’t right!”

The Netroots conference, the nation’s largest gathering of liberal activists and organizers, is a natural base for Ms. Warren, whose message about economic inequality — in particular the burdens of student debt — resonates with this largely young, tech-savvy crowd.

Dozens lined up to get signed copies of her new book, “A Fighting Chance.” (Some said they had no interest in Mrs. Clinton’s recent memoir, “Hard Choices.” “Who wrote that?” one man asked.)