If congressional Democrats don't do anything in the face of the mountains of evidence of criminal activities documented in the Mueller Report, they are flatly giving up on the Republic.
If they push for an impeachment of President Trump in the House that will fail in the Senate, many fear an electoral "backlash" similar to the vote against the impeachment of President Bill Clinton.
Lisa Blunt Rochester would like you to know that she aware of the fact that Trump is a corrupt, disease-ridden dog of a President*, but she wants to hear directly from Mueller before calling for impeachment outright.