Urging supporters to organize and resist the agenda of President Trump, Massachusetts Sen. Elizabeth Warren and Vermont Sen. Bernie Sanders headlined a political rally Friday night at Boston's Orpheum Theatre.

"We got to fight," Warren said. "We got to be in the fight, we got to be willing to go into the fight. We have to fight if we're going to win."

That pretty much summed up the message Warren and Sanders delivered to about 1,600 enthusiastic partisans. The event was organized by Our Revolution, Bernie Sanders' effort to continue his grassroots political movement that almost delivered the Democratic presidential nomination to him last year.

Warren, who was introduced as "a working class champion," was the warm-up act. She made the point that with Republicans in control of the White House and Congress, progressives like her and Sanders have few legislative tools at their disposal. But Warren says public activism and resistance is making a difference — and for that she offered a big thank you.

"To everyone in this room, and everyone around the country who got up and fought back the biggest assault on health care in this country — and won!" Warren said.

Sen. Elizabeth Warren speaking to a crowd of supporters Friday night at the Orpheum Theatre. (AP Photo/Steven Senne)

The stunning Republican failure last week to deliver on a major campaign pledge to repeal and replace the Affordable Care Act, also known as Obamacare, has given Democrats like Warren something to cheer about — even though that failure had as much to do with opposition from conservative Republicans as it did from Democrats. Still, Warren says, it is energizing popular opposition to the Trump agenda.

"We believe that health care is not some frivolity available for the rich. It is a basic human right for every human being!" Warren told the cheering crowd.

It felt like a campaign event — especially when Sanders took the stage.

The post-election Sanders is much like the pre-election Sanders: he's still advocating for a $15 minimum wage, tuition-free public college, government-provided Medicare for all, while blaming Republican policies for growing income inequality.

"Their greed is destroying this country and tonight we tell them enough is enough!" Sanders said.

Sen. Bernie Sanders addresses rally attendees Friday night. The event was organized by Our Revolution, Sanders' grassroots political organizing effort. (Steven Senne/AP)

Sanders was careful not to blame those who supported President Trump. He said "Trump didn't win" the election, the Democrats lost it. He pointed out that in recent years, Democrats lost control not only of the House, Senate and White House but also some 900 legislative seats across the country. Sanders says it's time for a "fundamental restructuring of the Democratic party."

"We need a Democratic party which is not the party of the liberal elite but a party of the working class of this country," Sanders said.

Sanders says a grassroots progressive agenda can resurrect the Democratic party. It's a message that he and Elizabeth Warren will continue to deliver as they both face re-election next year. Warren, meanwhile, continues to face speculation that she could be a candidate for president two years after that.

In Boston Friday night, Sanders was interrupted more than once with chants of "Bernie 2020."