Hayden, a former California lawmaker who 50 years ago helped launch Students for a Democratic Society, was joined at the 10th anniversary meeting of the Progressive Democrats of America by other national figures in progressive politics, including populist Jim Hightower, Vt. Sen. Bernie Sanders and radio host Thom Hartmann.

After the death last month of PDA’s guiding light, Tim Carpenter of Northampton, the event took up the task of honoring his years of political activism.

Conor Boylan, PDA’s co-executive director, said about 400 people registered for the two-day conference.

Saturday’s session at the First Churches closed with tributes to Carpenter. But speakers throughout the day repeatedly cited his political work.

Hayden, who spoke in a program about influencing Congress, said that if Carpenter had lived at the time of the American revolution, he would have been characterized as a member of the “motley rabble” — words John Adams spoke at the Boston Massacre trial.

The nation’s founders wanted to overthrow a king, Hayden said, but resisted rule by a “majority faction.” For that reason, Hayden said, the pursuit of political equality and economic democracy has for centuries required “a very long push, with a lot of Tim Carpenters along the way.”

Hayden noted President Obama’s reference, in his second inaugural address, to Seneca Falls, Stonewall and Selma — three political movements for political liberation. “Great politicians depend on social movements for their rise and very existence,” he said.

Such movements, he said, start outside government, but hold the power to change laws and the direction of government. “And one way or another, (popular political demands) would be settled on the inside. It was history. It was the way things worked.”

U.S. Rep. James McGovern told the PDA audience that Carpenter, a regular in the halls of Congress who would occasionally agree to put a sport coat over his political T-shirts, was able to buck him up in low moments. Carpenter and the PDA pushed to extract the U.S. from the war in Iraq and compel Obama to hold to a pledge to remove troops from Afghanistan by the end of this year.

“He’d ask you to do even more … keep on pushing, keep on pushing,” McGovern said of Carpenter. “It was about getting a vote and moving forward. It was about results. He was a citizen in the truest sense of the word.”

“These are tough times. We’re dealing with a crazy Congress, to put it mildly,” McGovern said. “Don’t ever underestimate the power that you have. … Your presence on Capitol Hill is important and it needs to continue.”

Steve Cobble, an associate fellow at the Institute for Policy Studies who helped found PDA in 2004, said Carpenter used an “inside-outside” strategy that combined the “idealism of the streets” with concrete legislative skills.

Carpenter eagerly engaged in civil disobedience and protests, Cobble said, but also relished conversations about policy and legislative strategy in Washington, D.C. “He was one of the greatest organizers I’ve ever met.”