A better solution would be to devolve the country and re-establish the states as sovereign. A return to the Articles of Confederation may be a solution. This is no more out of the ordinary than proposals for splitting the nation into two or more countries, and would be more peaceful.
I understand the fundamental point you are making about the ideological divide known to exist between liberal urban metropolitan centers and conservative suburban and rural areas. Maybe we would have to sort out the who-belongs-to-who issue at the county level. (Which, based on the pattern of the last several Presidential elections, would probably make Red Nation even larger territorially.)
This approach, of course, would make present state borders obsolete. It would also require state secession conventions agreeing to divide up the state territory in this manner. This is pretty unlikely as politicians understand that unsupported urban centers are fundamentally resource-less traps. Just as with the original Confederacy, secession would probably be an all-or-nothing proposition at the state level.
If you have read the Articles of Confederation (and I assume you have), you already know how inadequate they were and why, after a decade of trying, the US political class found it easier to simply abandoned them as a failing effort and start over from scratch with the Constitution. This is an important point to remember when hearing or reading someone waxing eloquent about the “genius” of the Founding Fathers; they got the organization of the national government badly wrong the first time around. In many respects, that failure was an important step to the success and longevity that the subsequent government has enjoyed.
Even then, we still had a very bloody civil war.
I would hope that, if it came to it, the new Red Nation would simply adopt a close version of the Constitution of the United States as its own constitution.
Given their proclivities, we know that the subsequent Blue Nation constitution, rather than adhering to the existing document, would probably read more like some liberal’s fascist wet dream for proletarian government.