Perhaps. Keep in mind that’s assuming you could get half of the Democratic caucus to rally behind the same new party. Splintering is counterproductive. Additionally, that’s only enough to get an effort off the ground. Current Democratic and Republican votes are roughly equal, neither the remaining half of the Democratic party, nor the half that forms a new party, will have the numbers to keep Republicans in check. You’d have to grow this new party quickly, including peeling off Republican voters. This is not a trivial task.