>>516049663
Following up on the siege idea. The left wing cities are very much powder kegs. Super high racial tension, with violent nonwhite groups ready to riot. People are heavily unaccustomed to scarcity and would collapse like a tin house under the slightest bit of pressure. The populations are very concentrated and heavily dependent on a fleet of trucks moving in across the highways.
They would have to use what military assets they possess to secure the highways, which are long and tenuous paths. Particularly if the highways go through hills, or wooded areas, they would be ripe for guerilla strikes.
If the cities were cut off from supplies, you could see them be forced to impose martial law. They'd have to warehouse the supplies in concentrated locations, prone to sabatoge. In fact they'd have to become utter dictatorships, which creates other possbilities. Like if you got manchurian candidates in there who secretly supported the right. Certainly an iron-fisted dictator is more likely to have right wing sympathies to some degree.
So in some sense the left has an advantage. But that advantage could fall apart extremely quickly and easily. The right would have to use smart tactics and subversion.