trump probably know they accepted funds from the Russians and thus they are complicit in not just trump's stolen election but in funneling dark money to keep other repugs ensconced in the House and Senate.

... has no choice at this point than to stand unified behind Trump, because doing otherwise will further the damage that they already anticipate will be done in the midterms.

Pulling their support now will lose them the die-hard Trump voters, and the GOP will be perceived as a party at war with itself - which is not conducive to getting voters to the polls.

Personally, I believe we will see a sea change after November. Whatever damage is going to be done to the GOP in the midterms will be a fait accompli, and Trump will then be expendable. No doubt the powers-that-be in the Republican heirarchy will start moving away from Trump, because they know he has no chance of being re-elected. His approval numbers are already historically low, and will undoubtedly sink lower when Mueller reveals his investigative findings. They have a much better shot at the 2020 GE with Pence - who can be profferred as the "scandal-free, upstanding, moral Christian" that Republican voters traditionally flock to.

Besides, the Republicans already got what they wanted out of Trump - the "jewel in the crown", the TaxScam that enriches themselves personally, along with their wealthy donors. That will keep the money flowing into GOP coffers for a long time to come.

I suspect we are going to find that some political action committees were funded with money coming from Russia and they knew it and did nothing.

and they're afraid of the possible repercussions.