I've held the theory for about two months now that every Republican is doing their own calculus about what actions cause the least blowback for them and are triangulating carefully to figure out how to maintain a career after this.

http://theweek.com/articles/698045/what-take-republican-voters-abandon-trump

The calculation will be slightly different for each member of Congress, and you can predict what they'll do by looking at their district. For instance, Rep. Barbara Comstock (Va.) is one of the few Republicans who have been openly critical of the Comey firing; she is also almost alone among her GOP colleagues in calling for an independent investigation into the Russia scandal. Is that because she's personally some kind of bipartisan moderate? Hardly — she made her bones in politics as a knife-in-her-teeth opposition researcher, digging up dirt on the Clintons in the 1990s. But she represents a swing district in the affluent Virginia suburbs just outside Washington, D.C.; Hillary Clinton beat Trump in her district by 10 points. Which makes her acutely aware that defending Trump will threaten her re-election bid next year.

But right now, she's in a tiny minority. Meanwhile, the places where many conservatives get their information, like Fox News and conservative talk radio, are manning the barricades in Trump's defense. So everything your average Republican voter is hearing convinces them that the president is right and this is all nothing but a fake scandal drummed up by Democrats jealous of how great Trump is making America.

There may come a point where the cracks in Republican unity begin to grow wider. But it will only happen when elite Republicans see it in their own interest to jump ship.

I'm more optimistic than Waldman; I think the majority of Republicans recognize that this ends badly but it's much easier to be wrong together than right alone. Just ask literally everyone who voted for the Iraq War.