It's only going to get worse for Democrats, page-16

"crime isn't the only criteria for impeachment."

No, 'orange man bad' will suffice, which is why the Senate shouldn't waste their time on it.

"Wouldn't the trial also consider if Trump had a defence for the obstruction he committed"

No, the SCOTUS is ruling on the legality of the Congressional subpoenas, as they should.

https://abcnews.go.com/Politics/supreme-court-trump-subpoena-challenges-term/story?id=67623875

President Trump has clearly done nothing wrong and there is no reason to continue the sham.