https://fas.org/sgp/crs/misc/RL33229.pdf
https://fas.org/sgp/crs/misc/RL34716.pdf
More sauce on the status of Representatives and Senators during the indictment and conviction process.
Since I started thinking about this expulsion process this morning before the recent Q posts, here are some more things I have been considering.
Again refer to:
https://fas.org/sgp/crs/misc/RL33229.pdf
https://fas.org/sgp/crs/misc/RL34716.pdf
Neither a congress m/w or a senator automatically loses their seats if indicted or convicted of a crime. It is up to the respective body to start a proceeding in committee to remove said official.
In the House, chairmanship of committees are surrendered under their internal rules, and upon conviction, membership of committees and the ability to vote in the House's business are gone.
The Senate has no such rules, except if a conviction occurs. Read the PDFs for details.
At this point it becomes an issue between the convicted official and their party - since it takes a 2/3rd vote to expel a senator or congress m/w, it would take cooperation from the offending official's party to get that done. A convicted official could keep their office, but their powers would be severely curtailed. An influential member of the House or Senate may try to retain their seat, but would effectively be counted as "not voting" until such they could become re-elected. Put 36 Democratic House members in this situation and the Republicans effectively take back control and majority. Therefore, it is to the benefit of the party to expel convicted members so presumably their state could select a new member (likely a member of the same party) to fill out the unexpired term (the methods of filling such vacancies differ from state to state).
Since the Republicans have a majority in the Senate, the danger to the Democrats comes as absences for litigation or conviction raise the number of Republicans present to the 3/5ths threshold. My math says the loss of 12 Democrat Senators gives the Republicans the super majority in the Senate.
Again, the fight between indicted/convicted Senators trying to keep their office, and the needs of the party will ensue.
In any case, there will be a time period between indictment and conviction that many of these Senators/Congress m/w will be absent to deal with their legal troubles and not available for floor votes or committee service.
This window of opportunity will allow for Republicans, with a few Democrat defections to accomplish a great deal legislatively - even if the majority is not regained in the House or a super majority is not achieved in the Senate.
Interesting times.
In any case, expect the remaining Democrats to be a lot less combative and more open to making deals after the first group are carted off.