The Republican playbook is now totally clear.
It has nothing to do with evidence.
It has everything to do with making the process partisan by not engaging with the evidence. They will use this to justify a partisan trial in the senate.
In so doing, they will implicitly end the constitution, democracy and the rule of law in the US. If one party, the GOP, will not consider evidence against its own representative, there's nothing but partisan advantage in play. You can justify cheating on elections, and there is no cost to doing so. How, then, do you get a result people will be willing to abide by?
Next step after that, sadly, is the recourse to violence. I wish the US would split peacefully, because staying together is not working, and staying together by dint of civil war is not a great way to impose peace.