Splitting the nation is the best shot at letting half the country avoid living under fascism and doing it peacefully.
While this approach appeals to emotion, I don't think either side will find that a split will be as "glorious" as they imagine. Here's how I see it playing out.
Blue side: One of the biggest issues for the blue side after a split will be an immense exodus of law enforcement, first responders and military. Most of these individuals will flock to the red side. Even if you could somehow negotiate a fair split of the military arsenal and nukes (what happens to the overseas bases and personnel, btw?), it doesn't matter if you have 1000 planes, but no pilots to fly them. I suppose the sheer number of nukes might serve as a decent deterrent initially, but the blue side would be vulnerable to immense crime internally as well as the usual threats from external bad actors. I will assume, for the sake of argument, that there will be some sort of "Non-Aggression Pact" with the red states. But imagine large cities with either a minimal police force or none at all. Second, while true that the blue states tend to generate most of the current GDP, they would undoubtedly need to raise taxes (already high in these areas) to try to deliver on popular liberal policies (universal healthcare, free college, etc). Now you might argue that this might be EASIER to do after a split since you'd have less states/population to try to cover, the most logical conclusion is that taxes would need to go up. This is even more likely when you consider that the blue side could also potentially, depending on the geographical split, lose most of the farmers/crops/food. While the blue side might still retain a lot of farmland, would the remaining population volunteer to harvest? Or would the blue side just increase imports of food? The latter would definitely add to increasing taxes. And if it doesn't work out, a worst case scenario would be food shortages or even famines. Now imagine that in the backdrop of many large urban centers also lacking adequate police forces. Anarchy could ensue. In short, the blue side could be looking at ending up less safe, with more crime, increased taxes/cost of living and possible food crises.
Red side: Prepare for a massive brain drain. Virtually all of healthcare, teachers, academics, etc will leave for the blue side. Now some on the red side may even celebrate this, but this will ultimately leave them a sick, sick country. Imagine no vaccinations required at all, or even banned altogether. Once eradicated diseases now totally endemic and uncontrollable. Imagine traveling hundreds of miles to see a simple primary care doc. Need a subspecialist or a surgery/complex medical procedure? Good luck. Hell, you might have to go "international" to the blue states to get that done. All this in the backdrop of zero healthcare coverage, unless you can pay for it, and it will be super pricey. Many red states already have mother-infant mortality rates that rival those of developing countries. Now that skyrockets everywhere. Without blue states subsidizing red states, they too will need to raise taxes. Think Texas and Florida will continue to have no state income tax? Think again. They will need a massive influx of money and that will have to come from taxation.
Bottom line is that a split leaves both sides more vulnerable, sicker, poorer and a with decreased quality of life (for different reasons). And I haven't even touched on a myriad of other issues related to manufacturing, borders, international relations, etc. There are probably endless layers of complexities to something like this.