Donald Trump and Billy Bush.

The election of a Democrat to a Senate seat in one of the most Republican states in the country is the culmination of an extended linear progression of catastrophic decisions, beginning with Donald Trump’s decision to open up the seat by appointing Alabama senator Jeff Sessions attorney general. (That decision, of course, is coming back to haunt Trump in even more painful ways.) It is possible to imagine a similar chain of events, in which Donald Trump’s recorded confession of sexual assault leads to his party’s loss of the House in the 2018 midterm elections.

Trump’s confession, which matched behavior reported by several of his alleged targets, at first seemed so momentous that it would compel him to abandon his position on the ticket. But after the handful of wavering Republicans mostly swallowed or recanted their doubts, allowing Trump to win, it seemed to mean nothing. In fact, the impact simply played out on a time delay.

The simmering rage at the election of an unqualified misogynist over the highly qualified prospective first female president produced a deep backlash in politics and culture. The willingness of Harvey Weinstein’s victims to speak out against him can be traced to that frustration.

The horrific revelations of Weinstein’s systemic abuse unleashed a torrent of allegations against powerful men. At first, the reporting was concentrated in fields with liberal cultures and where female reporters had the best access: entertainment and the media itself. But it is quickly spreading elsewhere, particularly to an institution with high levels of public accountability and male ego: Congress. Reports indicate forthcoming exposés of sexual harassment by some two dozen more members of Congress.

Assume for the sake of argument that men of both parties are equally likely to engage in sexual harassment. That would mean most of the harassers will be Republican. Republicans hold 241 of 435 House seats. And they are disproportionately male; there are 219 male Republicans in the House, and 132 male Democrats. The Senate has 47 Republican men and 32 Democratic men. Republicans are therefore likely to constitute a majority of the reported harassers.

What’s more, the impact of the reports will not be felt equally. It will hurt the majority party much more. The reason is that 2018 is shaping up as a wave election. In wave elections, the out-party usually loses very few seats. It is the in-party that loses. If Democrats are forced to step aside, they can easily be replaced. Republicans who have to step aside cannot. Incumbents pressured into retirement will open up seats that might otherwise not have had competitive races.

The impact of a wave election helps Democrats on both offense and defense, then. If your party is benefiting from a wave, you want to open the field as widely as possible. Losing some of your own members is fine — it’s the best possible year to cycle out your incumbents and put new blood in place. And it’s also the most opportune time to contest seats that might normally be out of reach.

So far, the two parties have responded to allegations of harassment differently. Democrats have turned against their own members facing allegations and forced them to resign, while Republicans — following Trump’s precedent — have largely abstained. But that is not an advantage for Republicans. It is a disadvantage. It forces them to field scandal-tarred candidates, not to mention a scandal-tarred party. You need look no farther than Roy Moore to observe the costs of the tough-it-out approach.

Facing down evidence of harassment with implausible denials may have worked for Trump. But the bill may still come due. It would be fitting punishment if he lost control of one or both chambers of Congress — and became exposed to investigations and oversight — as a result of a cultural reckoning Trump set off himself.