The independent senator from Vermont attracted more than 2,500 people to a convention center here on Friday night as part of his continued quest to lead a "political revolution" and win the Democratic nomination in a field that also includes Hillary Rodham Clinton.

It was by far the largest draw in Iowa, the nation’s first caucus state, by any White House hopeful this cycle — though there were plenty of Sanders fans in the crowd who came across the river from Nebraska.

Still, by any measure, it was impressive gathering and the latest to underscore the strength of the Sanders phenomenon. Earlier this week, 10,000 people showed up in Madison, Wis., to hear Sanders, a self-described democratic socialist, decry the "grotesque level" of income inequality in the country and the influence of the "billionaire class" on its politics.