Many in the GOP have put up with a lot from Trump because of the strong support from his base but now he's getting in to defense industry stuff. Perpetual War is a very serious business and they can't use chemical attacks to dupe him in to changing his mind 3 times in a row without being too obvious, so he's gone through with it this time. You already see rumblings from people like Powell and Graham, the latter of which has been a staunch Trump supporter since McCain's death, and the rumblings are going to get louder as time goes on and every dead Kurd gets its own headline on CNN and Fox alike. I think getting out of Syria is the right thing to do but some very powerful people with very deep pockets disagree with me, and with Trump. Republicans who would not normally want to impeach and remove a president from their own party may start thinking differently as they realize this impeachment thing gives them a chance of getting rid of Trump without having to have the JFK discussion.