They will have one, there are less of them supporting the president behind the scenes at this point than you think. Very few have come out to publicly support Trump. Rubio, Cruz, Barrasso, Ernst, Braun, Boozman, Cassidy, Crapo, Cramer, Enzi, Daines, Fischer, Gardner, Murkowski, Collins, Portman, Romney, Rounds, Tim Scott, Sullivan, Wicker and Young have all been very very quiet or vocal against the president. A good amount of these Senators are secretly working against the President. They are scared to go public, and might not do so, but many of them are trying to find a way to sabotage him.
I wouldn't hang your hopes on Conservatives doing the right thing. In the end, fascists and Nazis will always unite around a demagogue.
Better to go into it assuming the GOP will speedily acquit, then craft the 2020 election strategy around that sham acquittal.
The GOP is totally fucked here.