Unless you want to give newyawk 6 senators!!!!!
I dont think that the extra senators would automatically be libs though. If youre treating it as seperate states then the senators would have to represent and be elected by, the new states. The political reality is that states like NY, PA, and IL are blue states as a whole, but most of the state outside of the large metro area (NYC, Chicago, Philly) that dominates the state is pretty conservative. Im not sure libs would risk having more republican elected from the new states.