Given the results of elections in Virginia1 and New Jersey in recent days, there must be a shiver going down the backs of Republicans who can see their majority in both the House of Representatives and the Senate going up in smoke if such trends continue until the midterm elections in November of 2018. This must worry them and their donors significantly, to the point where they may be considering drastic action.
It is clear that there was massive intervention by Russian troll farms in the US presidential election, and the Republicans have given their imprimatur to what could be construed as an illegitimately elected president. To retrieve any semblance of a possibility that they will not be demolished at the midterms, something drastic needs to be done. This is perhaps even more urgent for the Republicans because, while there was a fairly solid 30%+ support for Trump even after many of his stupid actions, that support is now slowly declining, and support for him online has largely disappeared, with only rare diehards coming to his defence against only some of the more strident claims of his stupidity, ineffectualness and illegitimacy2.
It is quite possible that the Mueller investigation will indict more members of the Trump campaign team, and even members of the White House staff. If the latter is the case, and they are pardoned by Trump when charged with or convicted of federal offences, then the Republicans will lose any credibility. It will be perceived that they are simply unable or unwilling to do anything to combat the Russian interference. What the Republicans need to do, is to somehow remove Trump (either by impeachment or using the 25th Amendment), then allow the Mueller investigation to proceed, and neglect to pardon any of those convicted. That will be their only possible route to salvation. If that does happen, then they will have to start looking after the people and not just their donors.