(CNN) Al Franken's fall from Democratic party grace, and a perch where he stood among its most popular figures, came abruptly, a confounding plunge -- and to many Democrats, a stinging betrayal -- following his long and meticulous ascent from "Saturday Night Live" comedian to national politics.

In less than a month, Franken went from a formidable 2020 presidential prospect to the brink of unemployment, a would-be liberal lion cast out into an early winter, even, as Franken pointed out ruefully on Thursday, Republicans accused of worse sit in the Oval Office and, perhaps soon, among his Senate colleagues.

His decision to leave came under pressure from his Democratic colleagues, following yet another allegation of sexual misconduct. The Minnesota Democrat announced on the Senate floor he will resign in the coming weeks, saying "it has become clear that I can't both pursue the ethics committee process and at the same time remain an effective senator."

Franken's departure comes three weeks after he was first accused by a morning news anchor in California of forcibly kissing and groping her during rehearsal for a USO tour in Afghanistan in 2006, about two years before he was first elected. Days later, another woman came forward, telling CNN that Franken inappropriately touched her while taking a photo at the Minnesota State Fair in 2010 -- when he was a sitting senator.

On Wednesday, shortly after a seventh accuser spoke out, the dam broke . Thirty-two Democratic senators had called on Franken to leave by the end of the day, a drumbeat led by the women of the caucus and cemented by Franken's close friend, Minority Leader Chuck Schumer. In a Facebook post , New York Sen. Kirsten Gillibrand wrote, "We must not lose sight that this watershed moment is bigger than any one industry, any one party, or any one person."

Franken vs. the Norms

Franken's long transition from comedian and political satirist on SNL, where he spent 15 seasons over parts of three decades, to the United States Senate got a kickstart in 1995, when he left the show, for good, after Norm Macdonald beat him out for the coveted "Weekend Update" anchor slot.

"In retrospect, they made the right decision," he told comedian and podcast host Marc Maron earlier this year, "because I was wearing my liberal bias on my sleeve."

The next Norm in his path wouldn't fare so well.

Franken went on on to star in "Stuart Saves His Family," a movie based on his famous SNL character. It was a flop. His future wasn't on the big screen -- it was in politics. By 2003, with the release of his best-selling "Lies: And the Lying Liars Who Tell Them," Franken had established himself a leading liberal pundit. His initial, tempered support for the Iraq War, which he would go on to criticize and eventually label a mistake two years later, mirrored the party's broader shift left.

But it was the death of Sen. Paul Wellstone, a liberal Democrat, who was killed in a plane crash in October 2002, and the election of Republican Norm Coleman to his seat less than two weeks later, that stoked Franken's electoral ambitions.

As he recalled in his 2017 book, "Al Franken, Giant of the Senate," it was a quote from Coleman in a 2003 Roll Call profile that set him off.

"To be very blunt," the Republican said , "and God watch over Paul's soul, I am a 99 percent improvement over Paul Wellstone." Franken read it; he was incensed.

"I'm sorry, but you don't say that about anyone who died within the last six months," he wrote in the book. "And, my God, you don't say it about a guy who everyone agreed was a compassionate, tireless champion of the little guy, a loving husband and father, and a colleague whom every senator recognized for his passion and decency."

When Franken was sworn in as a senator in July 2009, he took his oath with a hand on Wellstone's bible.

In a rush to get involved

The road to the Senate, though, wasn't quite clear. Franken made waves in early 2004 when he bum-rushed a stubborn heckler out of a Howard Dean rally in New Hampshire. Word of the incident made headlines around the world and, for a lucky New York Times Magazine reporter, some incredible copy

"Franken hits the floor, wedges himself among a couple dozen legs and puts the man in a wrestling hold, grabbing (the heckler) at the knees," Russell Shorto wrote, giving a play-by-play of the scene in a subsequent profile. "That destabilizes him, and others now quickly push him down the aisle and out the side door of the theater. Franken gets up, looking dazed; his glasses are snapped in two."

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Not long after the piece was published, Franken would launch a radio show on liberal Air America radio, the doomed progressive answer to conservative talkers like Rush Limbaugh. "The O'Franken Factor," later renamed "The Al Franken Show," kicked off in March 2004 to mixed reviews.

"Franken has a slothful, pause-clogged delivery that doesn't lend itself well to punditry," a critic wrote in New York Magazine not long after its debut, suggesting comedians like Franken and Janeane Garofalo, another host on the new station, "just don't get the medium yet."

But even before his first show, Franken seemed less concerned with future of Air America or the potential for a career in radio than with taking on Republicans in Washington.

''I'm doing this because I want to use my energies to get Bush unelected,'' he told the Times about seven months before Bush was re-elected, defeating then-Sen. John Kerry in the 2004 general election.

Running, winning, and leaving

JUST WATCHED Al Franken's full Senate floor speech Replay More Videos ... MUST WATCH Al Franken's full Senate floor speech 11:29

Franken would move back to Minnesota with his wife, Franni, in late 2005. He was born in New York City but grew up in St. Louis Park, a suburb of Minneapolis, before going back east, to Harvard, for college. On February 14, 2007 , Franken signed off from his radio show with a word on things to come -- he would challenge Coleman, and seek to reclaim Wellstone's seat for the Democrats.

"I think I can do more," he said, after describing work he'd done on the campaign trail in Minnesota, "and so I'm going to run for the United States Senate."

Franken won the primary in a rout, with more than 65% of the vote. The general election would be much closer -- one of the narrowest and most drawn-out contests in American political history. In the end, Franken defeated Coleman, after a recount, by 312 votes. Nearly three million had been cast. Coleman launched multiple appeals but, on June 30, 2009, finally conceded. Franken became the 60th member of the Democratic Senate caucus, part of a brief supermajority that would eventually help pass Obamacare.

In an interview with "Late Night" host Seth Meyers last summer, Franken laughed about the thin margin, and how it made him careful in the company of his constituents.

"You have to thank everyone, and you can't lose a vote, like, 'Oh, that Franken,' now that he's a senator he thinks he's better than everybody," he joked as they recalled turning down a private room at a restaurant when Meyers' visited Minnesota.

Franken poses with Lindsay Menz, a 33-year-old woman who now lives in Frisco, Texas.

Some seven years before their conversation, Franken, during a visit to the Minnesota State Fair, took a picture with Lindsay Menz, who was there with her father and husband.

Menz, who told her story to CNN's MJ Lee in late November, said Franken "pulled me in really close, like awkward close, and as my husband took the picture, he put his hand full-fledged on my rear. It was wrapped tightly around my butt cheek."

Still, Franken won re-election comfortably in 2014. He was, by this year, one of the party's leading fundraisers and a top draw for liberal activist groups working overtime to counter President Donald Trump's agenda and Republican majorities in Congress.

Franken pledged on Thursday to keep speaking out, to not give up his voice along with his job. That seems unlikely -- at least for now. In a year of national reckoning, Franken will have his, out from the spotlight he'd chased for so long.