Democrats (Leftists) seem to have a real problem with the process for criminal prosecution.
First, there has to be a "crime" (...high crimes and misdemeanors...), THEN you can start to think about prosecuting it.
It's not that complicated.
You do not have to prove a crime has been committed in order to impeach a President.
All you need is the political will to do so.
As for breaking laws, the best Mueller will be able to do is try to catch Trump in a lie of some sort.
Proving Russian collusion was never the goal.
As for the GOP in the Senate, I would not put it past them to go along with the House.