Less than twenty-four hours after the news broke that comedian Louis CK had exposed himself to and masturbated in front of various women, HBO and FX cut ties with him. Similarly swift decisions were made regarding Harvey Weinstein, Kevin Spacey, Charlie Rose, and others in Hollywood and the media. Meanwhile, however, Roy Moore may yet win a Senate seat in the upcoming Alabama special election, Al Franken has called for and will be subject to a potentially lengthy ethics investigation, and no action at all appears to be occurring with respect to Donald Trump, despite credible allegations by thirteen women of sexual misconduct.

What accounts for the relatively swift purge of offenders from Hollywood and the media more generally (including NPR and The New York Times) but the slow to nonexistent action in Washington? Several factors may be at work, but, as I shall explain, the interaction of partisan polarization with relatively weak political parties appears to be the most potent.

Nonideological Factors

It goes without saying that the current wave of revelations includes men from many walks of life and with a variety of points of view. Business executives, actors, directors, producers, journalists, Republicans, and Democrats all appear to have behaved very badly over the course of many years, abusing their power to sexually harass, grope, and otherwise make life miserable for numerous women (and in some instances, men) they encountered. Although women are capable of abusing power to engage in sexual misconduct, the one common thread in the recent wave of revelations is that the perpetrators are men.

Not all of these cases are equally severe. To take two prominent illustrations from the 1990s, if one believes Anita Hill, then Clarence Thomas created a hostile work environment for her, a form of sexual harassment that is serious and should have disqualified him from a seat on the Supreme Court, but only a civil violation; by contrast, if one believes Juanita Broaddrick, then Bill Clinton committed rape, which not only should have disqualified him from the presidency but should have resulted in a substantial prison term.

In addition, the evidence in each case differs. Thomas and Clinton denied the respective allegations of Hill and Broaddrick, just as Trump and Moore deny the respective allegations of the thirteen and five women who have (so far) come forward to give their accounts of how they were treated. By contrast, CK, Spacey, and Franken have admitted at least some elements of the charges against them. Our legal system values due process, and so it is appropriate that action be taken more quickly when the misconduct allegations are not contested than when they are.

There also may be at least some ideological cast to the reactions. Feminists (whether men or women) are more likely to be Democrats than Republicans, and thus—although Democratic politicians appear as likely as Republican politicians to engage in abuses of power of a sexual nature—Democratic voters may be somewhat more likely to banish their politicians for allegations of sexual misconduct than Republican voters are to banish theirs.

Yet ideology seems to be a marginal consideration. While Bill Clinton was in office, Democratic voters (and many independents) were largely uninterested in what were facially credible allegations by Broaddrick and Paula Jones of very serious wrongdoing by Clinton. Meanwhile, for his part, Republican Mitch McConnell has a solid record of standing up to abusers in his own party. He was the first prominent Republican to say he believes Roy Moore’s accusers and, as chair of the Senate ethics committee in the 1990s, he did not hesitate to investigate fellow Republican Senator Bob Packwood on charges of sexual harassment, leading to Packwood’s resignation.

Party Politics Explains a Lot

Although Republicans and Democrats do not exhibit large systematic differences in how they react to allegations of sexual misconduct, there remains the difference in reaction between the media world (generally swift) and the political world (generally slower to nonexistent). What explains that difference?

The short answer is party politics, but the long answer is somewhat more complicated.

Let us begin with elections. Nearly every jurisdiction in the United States has winner-take-all elections. In such a system, if you do not vote for the Republican, you effectively help elect the Democrat, and vice-versa. It is thus instrumentally rational for Alabama Republicans who find Roy Moore’s behavior distasteful or are even outraged by it to nonetheless vote for him over the Democratic candidate Doug Jones.

Suppose you are an Alabaman who, for whatever reason, favors GOP priorities like tax cuts for very wealthy individuals and corporations, the destruction of the natural environment, eliminating health insurance for the working poor, strong protection for firearms owners, crime control methods that target African Americans, and the appointment of more Supreme Court justices willing to overrule abortion rights and gay rights. You probably would not want Roy Moore to be a chaperone at the junior prom at your daughter’s high school, but you might well think that his misconduct is an acceptable price to pay to preserve Republican control of the US Senate.

Similar logic explains why many committed Republicans who opposed Donald Trump in the 2016 primaries nevertheless voted for him in the general election. Indeed, it is easier to understand the decision of many Republicans to stick with Moore than it is to understand how the vast majority of Republicans voted for Trump. As one of 100 Senators, Moore cannot do much damage by himself, whereas, with Trump’s finger on the button, the thin-skinned egomaniac’s characterological defects pose a nontrivial risk of nuclear war with North Korea, which presumably Republicans no less than Democrats wish to avoid.

Why Not Trade Bad Party Members for Good Ones?

The more difficult question to answer is why parties and voters stick with their own bad actors, even when they could be replaced with good ones from the same party. Why didn’t other Democrats pressure Bill Clinton to resign during the Lewinsky affair, given that he would be replaced by fellow Democrat Al Gore? Why don’t Democrats now pressure Al Franken to resign, given that Minnesota’s Democratic governor would name a successor?

At least two factors appear to be at work. First, even if the parties do not differ that much systematically in how they react to allegations of sexual misconduct, there is a tendency on each side to see such allegations through a partisan lens. Democrats are more likely to believe allegations against Republicans than against Democrats, and vice-versa.

Second, although partisanship has increased in recent years—partly due to gerrymandering and partly due to geographic sorting—the US continues to have relatively weak parties, especially compared with countries with parliamentary systems. Voters do not simply pull the lever for a party; our system of primary elections and largely decentralized campaigning means that senators, representatives, and presidents come to Washington with their own backing. Indeed, being perceived by voters as independent of the party “establishment” can be beneficial to a politician. Accordingly, even if it would be better for the Democratic Party, all things considered, for Al Franken to resign his Senate seat, the Democratic Party cannot act without some measure of cooperation from Franken.

Likewise for the president. Given President Trump’s historically low approval ratings, the Republican Party would likely be better off were he to resign in favor of Mike Pence. But by contrast with parliamentary systems in which the prime minister can be removed by a vote of no confidence, the framers of the US Constitution made impeachment and removal difficult. While the Twenty-fifth Amendment adds a mechanism for the removal of an incapacitated president, it too is difficult to invoke over the objection of a president who claims to be of sound mind.

Accordingly, the answer to the question why Washington has been slower to respond to sexual misconduct revelations than Hollywood is, at least in part, the Constitution.