If there were a viable third party in the US (I know, I know) that got, say, 10-20% of the seats in Congress, how would committee assignments work? Would the Republicans and Democrats freeze them out? Can they freeze them out? Or is there some obligation for them to allow participation of this third party?
Just wondering how that would work in the hypothetical.
I think it would depend on which side they were more closely aligned with. This wouldn’t be an issue for parties to the left of the Democrats or right of the Republicans. Bernie, for example, probably gets his assignments the same way other Democratic senators do. Things might get trickier with some kind of Moderate party.
The organization of Congress is whatever a majority of each Chamber agrees to. Right now House Democrats could vote to give Republicans no committee assignments. They don’t because they know what would happen the next time they’re in the minority.
Typically the small number of third-party Representatives and Senators have “caucused” with one of the major parties and been treated as such for the sake of committee assignments. It’s hard to say what would happen if a third party became a sizeable minority in either chamber, but presumably that party would be able use their votes for Speaker/Senate Leadership to demand representation on committees.
Most serious third party people would shift from caucusing with one of the major parties to demanding to caucus as themselves (and anyone who wished to caucus with them) the moment they got anywhere close to the kind of representation that either of the two major parties get. I would guess that 20% would be high enough that you’d see a lot of that kind of behavior. “We don’t want to sit in your aisles and be treated as honorary Democrats (/Republicans). We want your causus to be forced to contend with our caucus. Now, about that infrastructure bill that you folks are so keen on passing. Our caucus would pretty much vote as a bloc in favor of it if you amend it so that the grant allocations favor small businesses and private individuals and not the corporate conglomerates who come to your feeding troughs”. etc.