Any dissident is going up against a huge pile of money and ingrained establishment that took years to build.
Sadly, the only way to do this would be for the voters in their home districts to decapitate the leadership by voting them out. Like 1994 in reverse.
Someone has every crumb of dirt on every one there, and is not afraid to use it. Call it blackmail, extortion, whatever, between the NSA, DOJ, and DHS, and All those little FBI files from back in the Clinton days, I doubt more than a handful up there aren't either completely compromised or are just running with the pack getting their slice of the pie.
Very few aren't owned, lock, stock and barrel, and I doubt many couldn't be disgraced or hauled off in irons within 24 hours the second someone dumps the stuff to the (also compromised or willing) media with the orders to pump it 24/7.