Blame is a luxury that can wait, no?
There are three options:
1/ Reclaim the Republican party.
2/ Move to/take over a smaller party.
3/ Create a new party from scratch.
While option 1 seems most appealing, it's a waste of time in my book. Political parties have a brand image and it's associated baggage, and the GOP's brand is pretty badly soiled. Not just by Trump, I'll add.
2 and 3 are both doable (3 has been done before, after all) but come with their own problem - fracture. Part of the GOP's problem was it wasn't an ideology in and of itself, it was a broad coalition of people with much of the same thoughts but differing priorities within those thoughts. Unless i is carefully done indeed, and with some mighty fancy footwork, you are going to wind up with 4 parties, all of whom can legitimately refer to themselves as conservative.
Me, I'd go for option 2 as the better choice, with the Constitution Party as the chosen vehicle.