Whether he's impeached or not, the GOP will suffer in both cases, either for still sticking to Trump or for abandoning him. I think that impeaching him would be a better way to get out of their problems in the long term. For the Democrats, it might be strategically better if the impeachment fails by not enough republicans voting for it.
Trunps lawyer complained about the issue being political. Yes, it is a political issue, but that's how it's meant to be. If it was solely a juristic matter, a court would decide about it right away. Besides, Trump can be happy that it's a political and not a juristic matter. He better shouldn't count on those Supreme Court judges he brough into powerr himself. They are in the jury for life, so there's no rational reason for them to return any favors and I don't even think that they owe Trump anything. Apart from that, returning favors by making certain court decision is criminal, isn't it?
What about those other figureheads in the riot BTW, like Trump's son?