When the framers nationalized and consolidated the Union into one government, they obliterated federalism. The big states all demanded, and got, proportional representation.
It would make sense for like-minded, similar states to band together. Thought bubble----what if the Dakotas, Iowa, Nebraska, and Kansas united into one state? Then they might have some pull.
Perfectly constitutional, if the states and Congress agree.
How these states would increase their clout by reducing their representation in the Senate from 10 to 2, and their votes in the EC by 8 requires math that is beyond my skill level.