Sen. Al Franken (D-Minn.) is officially stepping down. In a Wednesday speech, the senator ended speculation that he would not actually follow through on his promise to resign in the face of multiple allegations of unwanted and inappropriate sexual contact, both from before and during his political career. On Jan. 2, he'll relinquish his senate seat, to be replaced by Lieutenant Governor Tina Smith (D).

Franken's resignation will not change the balance of power in the Senate, but it will change the dynamics of 2018. Minnesota was once a true-blue state, but it has been trending redder and redder over time, going from on average 15 points more Democratic than the country in presidential contests during the period from 1976 to 1988, to being less than 4 points more Democratic than the country on average during the period from 2000 through 2012 — and being marginally less-Democratic than the national popular vote in 2016. Democrats will now have to defend both Senate seats as well as the governorship; they'll also be fighting in five competitive House elections, three for seats held by Democrats, two for seats held by Republicans.

Even as their hope fades nationally, Republicans are energized in Minnesota. Democrats will want their strongest nominee to hold Franken's seat — possibly the incumbent Smith, but don't count out Attorney General Lori Swanson if she doesn't prefer to run for governor. More generally, they'll want to deploy every weapon they've got to triumph across the board in this key battleground state.

Will Al Franken be one of those weapons?

The question sounds ridiculous on its face. Franken resigned in order to avoid being a demoralizing distraction to his party, and to blunt a possible Republican talking point about Democratic hypocrisy. In a year when even Republicans are looking at a number of female candidates to contest Franken's seat, at least one of whom has already declared, Franken's presence on the campaign trail would surely be an even bigger embarrassment than would his continued presence in the Senate.

Moreover, for all Franken's popularity with the national Democratic base, he was hardly an electoral juggernaut in his home state. He won his initial election in the Democratic wave year of 2008 by a whisker, and won re-election in 2014 with only 53 percent of the vote against a weak Republican challenger and two right-wing third party candidates.

But Franken himself clearly doesn't see things that way. His resignation speech was laced with resentment at having lost his party's confidence without having an opportunity to defend himself, a sentiment some of his colleagues have echoed. And before stepping down he's planning to give a series of high-profile speeches about what he's learned in his eight years in Washington, and what he thinks we need to do to secure America's future. That's not the behavior of someone slinking away from the limelight.

The most common strategy for ambitious politicians to follow when caught in a personal scandal is to deny everything and fight it out. That's what Donald Trump did, and that's what Bill Clinton did before him. But politicians who resign and then come back can sometimes have a meaningful impact on their races, and on the issues that forced them from office, even if they never make it back in.

Gary Hart, once the front-runner for the Democratic presidential nomination, dropped out of the race in May of 1987 after the press, who he had dared to follow him, uncovered proof of a widely-rumored extramarital affair. But he returned to the race in December. While that return was unsuccessful, it unquestionably highlighted for Democrats just what a talent they had lost in Hart — and thereby made both the party and the press less-willing to terminate Bill Clinton's campaign when he ran into similar trouble on the eve of the 1992 New Hampshire primary.

More recently, Anthony Weiner resigned his seat in Congress after tweeting sexually explicit photos of himself, only to launch a comeback bid for mayor of New York City less than two years later. That latter bid collapsed in the wake of additional sexting scandals, but not before Weiner was able briefly to knock outgoing mayor Michael Bloomberg's preferred successor, Christine Quinn, from the top of the polls. It is possible that without the turmoil Weiner brought to the race, Bill DeBlasio would never have found the opening to unite progressive opposition to Quinn, and ultimately win the mayoralty. (On the other hand, had Weiner's wife, Huma Abedin, left him after the original scandal, Weiner would have been in no position to damage Hillary Clinton in her presidential campaign's waning days.)

Will Al Franken go gently into that good night? Only he knows. But if he doesn't, he could have a meaningful but unpredictable impact on any number of Minnesota races.

If he polls well against Smith, for example, that would reveal a profound weakness in an appointed incumbent, and thereby encourage other entrants into the field. By contrast, if he runs for governor and gets crushed in the primary by Swanson, she'll only be stronger as a general election candidate. Even if all Franken does is be a good soldier, raising money for Democrats and tweeting one-liners against Republicans, his party will have to reckon with his continued potency and what that means about how serious they are about zero tolerance — or, alternatively, if he gets little traction, Franken will have to acknowledge that he blew it, and his time has passed.

Regardless, his presence would force a public argument over his transgressions, and their political importance. That's a debate worth having, and the political arena is the very best place to have it — because it is a political question.

If Al Franken had submitted to an ethics inquiry, there would always be suspicion that the Senate would protect its own, because Congress has protected its own, over and over. But if he resigns in bitterness over his unfair treatment, that bitterness itself could become a weapon — and one far more potent for the opposition than for his side.

In the end, it's the voters who have to endorse the proposition that the kinds of things Al Franken is accused of are truly intolerable.

I wonder if Franken wants to find out if they truly do.