In the wake of a new Washington Post report showing Republican presidential nominee Donald Trump speaking in very lewd terms about women in 2005, some Republicans are calling for Trump to step down as nominee. (Thomas Johnson/The Washington Post)

The revelation of Donald Trump’s three-minute, decade-old video in which he bragged about sexually assaulting women has achieved what his past controversies largely failed to do: rouse dozens of Republican lawmakers to grab life vests and jump ship. According to the running tally compiled by Daniel Nichanian, about 33 House and 17 Senate Republicans have declared that they will not support or vote for Trump for president.

The flurry of opposition to Trump is remarkable, albeit with precedent. (Moderates’ opposition to Republican Barry Goldwater’s 1964 presidential candidacy comes to mind.) Still, only a small portion of each chamber’s GOP conference has broken with Trump.

So which lawmakers have abandoned Trump? I used a simple statistical model to estimate which of the 246 House Republicans were most likely to do so.  Two clear patterns emerge in the figure below.

First, lawmakers are ever the “single-minded seekers of re-election” that Yale political scientist David Mayhew identified about 40 years ago. The better President Obama performed in a member’s district in 2012, the more likely he or she is to abandon Trump. Indeed, for the roughly two dozen GOP congressional members who represent districts Obama won, about half have jumped ship. (Not surprisingly, the jumpers tend to be far more moderate ideologically than their GOP colleagues.) Put simply, the more Democratic your voters, the more likely you are to jump ship.

Second, a disproportionately higher number of Republican women jumped off the Trump ship. About a quarter of GOP women in the House denounced Trump, compared with about 10 percent of Republican men. Importantly, more than ideology is at work here: On average, GOP congresswomen are only marginally more moderate than their male colleagues. Nor is the gender effect simply a proxy for lawmakers’ electoral motives: In the current Congress, the partisanship of congressional districts represented by men and women is nearly identical.

Instead, the surge of women abandoning Trump this weekend is a strong reminder of the cross-pressures on female GOP lawmakers, especially those who hail from conservative districts. As Michele Swers argues, women bring a different perspective to their jobs as lawmakers, prioritizing issues related to women, children and families — even as they compete on rival partisan teams. Trump’s video seems to have been a bridge too far for many female lawmakers, compelling them to break with their fellow partisans.

With the second presidential debate Sunday evening, more Republicans may yet follow suit. My hunch is that women and electorally skittish lawmakers are waiting on deck.