On a gorgeous fall day, surrounded by changing trees, a group of Bernie Sanders’ most ardent supporters held a political bonfire for the doomed Trans-Pacific Partnership outside the US Capitol building.

“RIP TPP!” the group chanted at the rally, organized by National Nurses United.

Trump – along with Sanders and eventually Hillary Clinton – was a forceful opponent of the trade deal during the campaign. Trump’s electoral victory is an effective death knell for the trade deal and has handed progressives’ their first major achievement since the election left the Democratic party in shambles and searching for a leader.

Nina Turner, former Ohio state senator and a vocal Sanders’ surrogate, teased the crowd before the senator’s arrival: “I’m still feelin’ a little somethin’, somethin’ … Some like it hot baby. ”

“I’m feelin’ the Bern!” someone shouted back.

In the distance, a small commotion erupted as a shock of white hair bobbed towards the stage, setting off a wave of raucous cheering.

The famously grumpy senator barreled through the crowd, flanked by aides and a crush of reporters who struggled to keep pace. Representative Rosa DeLauro of Connecticut, who spoke at the rally, attempted to embrace Sanders, but he didn’t slow his stride and nearly dragged her with him.

Sanders swept to the stage to wild cheers. Two young women waved a banner with his first name written bold letters. Attendees sported his campaign T-shirts, buttons and stickers. The revolution, it seemed, had reached Capitol Hill.

“I’m not here to blame anybody, criticize anybody, but facts are facts,” Sanders said, his voice building as he spoke. “When you lose the White House to the least popular candidate in the history of America, when you lose the Senate, when you lose the House and when two-thirds of governors in this country are Republican, it is time for a new direction for the Democratic party!”

The crowd cheered and applauded, melting into a familiar chant: Bernie! Bernie! Bernie!

“No – no, no. It’s not Bernie,” the senator said, waving his finger in protest. “I appreciate your love and it’s mutual … but if there’s any message I have today it is not Bernie, it is all of us today.”

It’s been a whirlwind week for the self-styled “democratic socialist”.

Since the election, Sanders has been a frequent face on cable news. He swept through New York earlier this week to promote his new book, Our Revolution. In many ways, Sanders has emerged from the party’s devastating loss as the face of the party’s future.

On Wednesday, the Senate minority leader, Senator Chuck Schumer of New York, rolled out the party’s new leadership team. In a testament to his growing influence within the party since challenging Clinton for the presidential nomination, Sanders joined the Democratic leadership team as chairman of outreach.

That a lifelong independent is playing a key role in rebuilding the Democratic party is a sign of just how strange Washington DC has been since the American people elected Donald Trump as president.

The businessman won the election by managing to sway disaffected white working-class voters in rust belt states, many of which Sanders won in the primary. Sanders has said that Trump effectively tapped into the anti-establishment anger that he harnessed in his bid for the Democratic nomination.

Moumita Ahmed, 26, who volunteered for the Sanders campaign in New York, said she had no doubt that the senator would have won had he been the Democratic party’s choice. But Ahmed, who wore a red shirt with Sanders’ face and the text: “Hindsight is 2020”, is not looking backward.

“Right now is the time for everyone to unite and not necessarily ponder what-ifs but what can we do moving forward to ensure that what happened in the primary never happens again,” she said. “We tried the establishment. That didn’t work. Now more than ever we need a strong left.”

Senator Bernie Sanders speaks during a rally on Capitol Hill. Photograph: Mark Wilson/Getty Images

Over the course of the last week, Sanders has aggressively inserted himself into the brewing ideological battle over the party’s future. The Vermont Senator, along with a number of progressive lawmakers, has endorsed Representative Keith Ellison, a liberal organizer from Minnesota, for chair of the Democratic National Committee.

He is also urging the party to work with a Trump administration on issues of trade, infrastructure and pay equity, but has vowed to vehemently oppose bigotry, racism and xenophobia, which featured prominently in the Republican’s campaign.

Sanders has joined more than 120 Democrats in demanding Trump rescind the appointment of Stephen Bannon, the white nationalist media executive, who the president-elect recently named chief White House strategist.

“I think that the president-elect has got to understand that many of the things that he said during the campaign, the ideas that he brought forth are terribly offensive, and frightening to millions and millions of people,” Sanders said on Fox News Radio on Thursday.

“This is a man who was the leader of the so-called “birther movement” trying to undermine the legitimacy of our first African American president. And I think he has to say to the American people, ‘you know what, I’m sorry. I said things that I should not have said. We are one country, we have got serious problems, and we’ve got to go forward together.”

At the rally, Sanders sounded a note of unity, imploring union members, immigrants, climate activists, criminal reform advocates and more to join the fight for equality in the Trump era.

“When we stand together, Donald Trump, nobody – nobody – is going to stop us.” Sanders said. “Let us go forward together!”

Sanders exited the stage and a mass of supporters lunged forward to try to capture a photo of the senator striding back to the Capitol. Revolution by the Beatles played softly in the background.