Would the slide into amorality of the Republican Party have happened regardless of Trump ?

Oh, they were already headed down the slope on their own. To comprise the most ineffective, obstructionist house in modern political times requires a serious lack or vision, sense of duty and simple decency. The day it became more important to win a game than fulfill their obligation to act in the best interest of their constituents, the party headed downhill.

Trump is simply the two-ton elephant they chained to the party.