Ihad predicted that Donald Trump would try to overturn the election results in every way possible, including the incitement of violence. But even I didn’t imagine how far the defeated president would go on 6 January 2021. Even in my wildest imagination, I had never contemplated that a violent group of extremists, many of them white nationalists inspired by a vile doctrine of racist and antisemitic hatred, would storm the Capitol and overwhelm the Capitol police, physically take over the US Senate chamber and threaten the lives of the vice-president and the speaker of the House. Being trapped in a room with other senators, guarded by police officers and FBI agents with machine guns, was a scene I never could have predicted – and never want to see again. But I knew then, as I know now, that the deep divisions Trump and his allies had opened up in America, and which they continue to inflame, make the possibility of more anti-democratic violence real. That was one of the many reasons why I later voted to convict Trump for inciting an insurrection, and why I would do so again. For weeks before and after Biden’s inauguration on 20 January 2021, thousands of national guard units from states across the country, including Vermont, established checkpoints around the Capitol and secured the perimeter. This was a far cry from the usual peaceful transfer of power from one administration to another that our nation was accustomed to. Instead of what we read about in eighth grade civics class, Washington on those winter days felt like a city beset by civil war. When I spoke with guardsmen and women, I was struck by the fact that they knew exactly why they were there. They were defending the constitution and preserving our fragile democracy. Not everything that happened in that epic moment was so consequential, as I learned on Biden’s inaugural day. I have been involved in public life for over 50 years. I have run for mayor, governor, the US House and the US Senate. I ran for president of the United States twice. But I have never received so much attention as I did when, on a bitter cold winter day, I took my place in the stands that had been erected for the inauguration of Joe Biden and Kamala Harris. As a sensible Vermonter, I was wearing a heavy coat and a pair of homemade mittens. Vermont, it’s fair to say, is not a “flashy” state in terms of attire. There’s a reason for that: Vermonters know it can get very cold in the winter, and they know how to stay warm. We are a practical and functional people. We wear boots, sweaters, warm coats and funny looking hats. Style is not our focus. Staying warm is. Like every other member of Congress, I had received an invitation to attend the ceremony on that 20 January. In normal times we would have been packed together on the west front of the US Capitol, facing the National Mall. These, however, were not normal times. We were in the midst of the worst pandemic in 100 years, and our seats were spaced far apart. We were wearing face masks. And the proximity to the 6 January insurrection made security a top priority. Frankly it never occurred to me to wear anything for the inauguration other than my warm Vermont coat, the coat I always wore, and the only one I had in Washington. It was a blustery day with the possibility of snow. And to keep my hands warm I had, as I always did, a pair of mittens in my pockets that were knitted by Jen Ellis, a schoolteacher from Essex Junction, Vermont. She had kindly sent them to me, and I gladly wore them on inaugural day. That was the whole story. Except. When I got back to my office after the ceremony I was informed by Mike Casca, my communications director, that a photo of me sitting alone in a mask and mittens had gone viral on the internet. That was weird. But it got weirder. There I was with my mittens on the moon, at the Last Supper, on the Titanic, alongside Forrest Gump, on top of skyscrapers. It turned out that the photo, shot by Agence France-Presse photographer Brendan Smialowski, generated more memes than almost any other taken in 2021. Who would have thought? Not only did the photo, and the many permutations it inspired, create a lot of smiles, it also enabled us to raise much-needed money for organisations that serve low-income Vermonters. Our campaign organisation sold T-shirts and sweatshirts with the photo that raised some $2m (£1.65m), which went to Meals on Wheels and other excellent agencies around the state. But after Biden was inaugurated I had more on my mind than mittens and memes. Thousands of Americans were dying every day from Covid, we were in the midst of the worst economic downturn since the Great Depression. Shops and restaurants were shut down. Unemployment was skyrocketing. People were going hungry and facing eviction. Congress had to act boldly. With Biden as president, we had the opportunity to put Trump’s malignant neglect behind us. And as chairman of the budget committee, I was in a position to make things happen… This is an edited extract from It’s OK to Be Angry About Capitalism by Bernie Sanders (Allen Lane, £22). To support the Guardian and Observer order your copy at guardianbookshop.com. Delivery charges may apply