It was a visceral cry at the moment of maximum peril for American democracy.

A furious mob had overrun police and was nearly at the door of the House of Representatives. Inside the chamber, Republican Paul Gosar was launching a spurious challenge to Joe Biden’s election victory in Arizona.

Then, at the back of the gallery on the second floor, Democrat Dean Phillips rose to his feet and screamed at the top of his lungs at Gosar: “This is because of you!”

The outburst was out of character for a “Minnesota nice” congressman with a reputation for moderation and working across the aisle. But a year later, Phillips remains convinced it was an urgent and necessary response to the deadly insurrection inspired by then president Donald Trump.

“It’s not my style to break decorum and to scream,” he told the Guardian, “but I have to say at that moment I felt the way that tens of millions of Americans did, which is there were people responsible for what was about to transpire and there are moments where you do what you got to do, and I had to do it. I don’t regret it one bit because it’s true.”

Phillips, 52, comes from a business background. He led a family-owned distillery – producing vodka, gin, rum and other liquors – and ice cream company. He was elected to Congress in 2018, representing Minnesota’s third congressional district, and is vice chair of the bipartisan Problem Solvers Caucus.

“I never imagined I’d be doing this,” he admits. “I woke up the morning after the 2016 election, saw the reaction of my daughters, who were 18 and 16 at that time – their fear, their tears – and I promised them right then and there I would do something, and here I am.”

On 6 January 2021, he had been advised that there could be trouble so told his staff to stay home. He watched his office TV “horrified” as Trump gave a speech urging supporters to “fight like hell” to overturn his defeat. He then walked to the House to begin certifying Biden’s election victory. But soon he received text messages from anxious family members showing video of protests forming outside.

“I asked my colleague, Tom Malinowski from New Jersey, to walk from the House chamber with me to look out the windows and a Capitol police officer literally screamed at us to get away from the windows and get back into the House chamber. We asked if everything was OK, and – I’ll never forget it – she said, ‘You’re in the United States Capitol. It’s the most secure building in the country’.”

They returned to the House chamber just as Speaker Nancy Pelosi and Majority Leader Steny Hoyer were being evacuated. Gosar was at the microphone, leading efforts to subvert his state’s electoral college vote, when the sergeant-at-arms urged members to take cover behind seats and prepare their smoke hoods – prompting Phillips to feel “fury” and let rip at the Trump loyalist.

While members on the House floor were able to escape, there was no way out for 20 sitting up in the gallery due to coronavirus safety measures. “I screamed at my colleagues at that moment to follow me to the Republican side of the chamber because I thought it would be safer,” Phillips says. “I thought the insurrectionists were coming for us.

“First, it was almost impossible to get through these railings; you either had to go under or over. But more than that, I recognized at that very moment that a lot of my colleagues couldn’t blend in. I’m talking about those of color. It really left an indelible mark on me.

“That whole day changed me, of course, as it would anybody, to recognise that privilege and the fragility of democracy and also a significant increase in my empathy for those who have endured trauma in their lives, which is life-changing.”

Rioters reached the doors of the House chamber but found their way blocked by an improvised barricade and Capitol police with guns drawn. After an ordeal lasting about 25 minutes, Phillips recalls, members in the gallery were led out by a Capitol police officer and through a maze of tunnels.

“We ran into the Rayburn lunch room and it was a bizarre moment because there were people just having lunch at the tables. The sun was shining in from the big plate glass windows and here we are, an officer with a rifle running with us into the lunch room and people just stunned, looking at us like, what the heck’s going on? Of course, the TVs moments later would sure change that.”

The group was then moved on to a committee room where they were finally safe. But their shared ordeal would stay with them. They now call themselves “the gallery group” and still meet regularly, sometimes with facilitators or therapists. “It’s been the most wonderful support group imaginable because we endured it together,” Phillips says.

On the night of 6 January, with the Capitol finally secured, they and other members returned to the House and Senate to finish the job and ratify Biden as president. For a fleeting moment, it seemed that Democrats and Republicans were united in completing the work of democracy and jettisoning the authoritarianism of Trump. But it was not to last.

In the year since the insurrection, some Republicans have embraced Trump’s “big lie” and his portrayal of the mob as patriots driven by a noble cause; others have simply remained tight-lipped and failed to denounce it. Phillips, who sees them up close during sessions of Congress, believes they are motivated by self-preservation of both position and personal safety.

“That’s perhaps the saddest part of all this. Many of my colleagues – especially those who voted to impeach, those who voted to impanel the January 6 commission, those who voted to certify the election – have received horrifying threats to their safety and the safety of their loved ones. It’s an unenviable position but it’s also our responsibility and duty. I understand self-preservation but I do wish principle would take precedence,” he says.

It has been difficult for Phillips to witness 6 January denialism as Republicans and rightwing media attempt to rewrite the history of what happened that day, variously characterising it as a “normal tourist visit” or an FBI “false flag” operation designed to entrap Trump supporters. The former president himself insisted that his followers were “hugging and kissing” police.

The Democrat says: “This is one of those rare occasions where I was there. I was inside. I heard the gunshot. I saw the remnants of the insurrection in the rotunda and went with [Congressman] Andy Kim at midnight that night to help clean it up when I saw him on his hands and knees alone.”

“I saw the body armour. I saw the clubs. I saw faeces. I saw the speaker’s office ransacked. I saw with my own eyes people on the ground under arrest. I saw the mob breaking in. I met with the officers who were subject to it since. I was there to bear witness to it and to hear people say it didn’t happen or it wasn’t a big deal or it’s time to move on, shame on them.”

Republicans’ denial of reality, and continued addiction to Trump, has raised fears that 6 January was the beginning, not the end, of American democracy’s near death experience. The party is imposing sweeping voter restrictions across the country and seeking to put “big lie” believers in charge of future elections. Trump could mount another bid for the White House in 2024 with many checks and balances no longer in place.

Phillips comments: “We are at the precipice of a very slippery slope and it’s a long way up the mountain when you’re building a democracy but it’s a fast ride down when it slips away. We collectively have to make a choice and a decision here, starting with the simple fact that this is not something that one side or the other can win.”

“If one side upends democracy and destroys its institutions and disrespects the rule of law, chaos will result, violence will result and everything that those propagating this claim is important to them – a strong, stable, secure, prosperous country – will have been lost. That’s why I try to be a voice of reason and a bridge builder, not a destroyer.”

A self-described eternal optimist, Phillips believes there is still a cohort in the Republican party that can find a way back to the mainstream. He describes Liz Cheney and Adam Kinzinger, Trump critics serving on the House select committee investigating 6 January, as “heroic”.

“I know there are more that share that sentiment that simply are not as public. I have confidence that we will see some type of restoration of principle, assuming American voters find that important.”

The congressman’s efforts to lower the political temperature include a series of “common ground” get-togethers in his home district that encourage mutual understanding between constituents across the ideological spectrum.

He says: “They’ve inspired me and made me more optimistic because I’ve discovered when, with some intention, you bring people together with disparate political perspectives and break bread, get to know each other and share life stories, common ground is readily available and easily discoverable.”

But in this age of polarisation and negative partisanship, there must be some awkward conversations? “We had an experience just a few weeks ago in which someone pulled up in what would be considered a vehicle that a Donald Trump supporter might be driving and someone who was on the far left of that person – in a very uncomfortable moment but it turned out to be a very productive one – acknowledged what she felt when she saw that vehicle pull into the parking lot and what she expected of the person who drove it.

“It took courage to share that. It took courage for the driver of the vehicle to listen to it. At the end of the evening, for both of them to recognise their shared humanity and shared interest in a safe and secure country, was a moment of great reassurance but one that can only occur if people stop stereotyping and actually start breaking bread together.”