The political demise of Susan Collins – a fixture of Maine and Washington politics for three decades – recalls the famous line in Ernest Hemingway’s The Sun Also Rises about how one of the novel’s characters experienced bankruptcy: gradually, then suddenly.

In the run up to Tuesday’s stunning Democrat “blue wave” election triumph, it seemed obvious that Collins’ 30-year tenure as Maine’s Republican senator was vulnerable to the challenge of Troy Jackson, the Democrats’ explicitly working-class candidate as voters prepared to unleash pent-up anger with Donald Trump’s presidency.

Rather like the Berlin Wall in the days before it finally fell in 1989, however, no one seemed to believe it could really happen until it did.

Collins, after all, had survived seemingly credible electoral challenges before and appeared primed – despite opinion polls showing a close race – to win a sixth Senate term, having once pledged to serve only two. She had become something of a state institution, with her assertions that Washington connections brought federal funds and contracts to Maine carrying weight with many constituents.

Jackson, meanwhile, seemed a less-than-polished prospect for a state that had previously sent such august figures as Ed Muskie, George Mitchell and Bill Cohen to the US Senate before they went on to become international statesmen.

Jackson’s candidacy had been founded on the withdrawal of the party’s original nominee, Graham Platner, whose progressive populist platform generated real excitement before the emergence of serious sexual misconduct allegations.

Platner denied the allegations, but withdrew from the race. Jackson, a former logger, meanwhile had just 101 days to campaign after being nominated as his replacement.

On the eve of polling day, one activist, Doug Emerson, was so skeptical of local voters’ willingness to jettison Collins that he festooned his car with Trump policy miscues he believed she had been complicit in, and parked it outside the senator’s office in Portland – Maine’s biggest city – in the hope that it would raise awareness.

Even as polls closed and the count got underway, hopes for Jackson’s success seemed restrained at the Democrats’ watch party. Early returns showed Jackson with a small lead, but within catching distance, even as previous Republican electoral bastions once thought impregnable fell to the gathering Democratic wave.

The realization that this elemental political force was about to sweep away Collins came late in the evening, when – with about 60% of the ballots counted – returns showed Jackson with a convincing lead. Within minutes, MS Now reported that Collins had called to concede; wild cheers and chants of “Troy, Troy” filled the ballroom at Portland’s Holiday Inn.

Amid the euphoria, it was left to Jackson to deliver a message of humble, down-to-earth populism that emphasized his trade union background and underlined that his unlikely triumph had been driven by grassroots discontent.

“You understood what it would mean to send one of your own to the United States Senate,” he told the crowd. “Donald Trump and the billionaires need to understand one thing very clear – something about your new senator. I don’t owe them a damn thing.

“When they threaten your healthcare, your livelihood, or your freedoms, I am going to stand up to them. You know where I’ll stand. You know how I’ll vote. And when you’ve got a question about it, you’ll be able to ask me yourself. I’m not acting like I’m the best thing that ever happened to the US Senate or anything like that.”

It was a promise of accessibility that critics say Collins never provided – despite her claims of independent-mindedness and protestations of frequently voting against Trump, who failed to carry Maine in any of his three presidential campaigns.

Jackson, who as a state legislator once opposed abortion rights, won the backing of pro-choice campaigners by stressing Collins’ 2018 vote for the conservative US supreme court justice, Brett Kavanaugh, who subsequently voted for the court’s ruling that overturned the historic Roe v Wade decision, which had previously guaranteed abortion rights nationally. Jackson placards reading “abortion is on the ballot” were widespread.

Trump, in contrast to his on-the-ground support giving stump speeches for multiple other Republican Senate candidates, did not visit Maine to campaign for Collins. Yet there was clear skepticism about her self-anointed image as a free-thinking critic of the US president. His shadow still loomed large.

Todd Cox, 63, a technology professional, who had previously voted for Collins, said “concern for the direction the country is going in” drove him to back Jackson this week. “We definitely haven’t become kinder and gentler under this administration,” Cox told the Guardian on Tuesday. “There’s a lot of bullying that goes on. It goes back to affordability. It’s the war in Iran – that shouldn’t be happening. It’s the disregard for the rule of law. It just seems like they’re thumbing their nose at it.”

One key campaign moment came in the first televised debate when Collins cited as an example of her willingness to defy Trump on tariffs from Canada her work in getting road salt exempted. “You can’t eat road salt,” Jackson replied tersely, a phrase that became a slogan used in Democrat campaign material.

It reflected a broader attack on Collins’ credentials as a champion of the state.

“She’s very good at letting us all know what she has done,” Elizabeth Wise, 59, a registered nurse working as a vote canvasser for Jackson said at a canvass event in Yarmouth. “But she has really been manipulating Maine voters into thinking that she is a moderate.

“She makes big deals for the very wealthy in the billionaire class and corporate America on the backs of very small deals that she brings home to Maine. It is a senator’s job to bring money back to their state, and other senators bring a lot more money back to their states than Senator Collins brings brings to Maine.”

Jackson now stands as a potential antidote, say his supporters. “The Senate has been an elite group of millionaires, and Troy comes from a working-class background,” said Cynthia Phinney, president of the American Federation of Labor and Congress of Industrial Organizations (AFL-CIO) in Maine, which made 65,000 canvassing calls on Jackson’s behalf during the campaign.

“Having a working-class person and a union member in the United States Senate is an historic change,” added Phinney. “People are ready to demand change that they haven’t got from their elected officials. It’s a moment in history.”