The characters are skimpy and one dimensional. The analysis of U.S. society is too simplistic to give a good foundation for the characters' motivations or clear goals for either army other than to win.
On the one side there are the militia types, who yearn for a government to push an agenda of ??? These small groups can organize secretly, band together and arm themselves (only the last part seems plausible) but the writer doesn't spell out what their objective is. He doesn't spell out why half of the military are supporting the coup attempt. They are just responding to a poorly regarded (despised by many, especially overseas) TV channel's call to arms. These people suddenly rise up and don't claim any agenda because they hadn't thought that far ahead?
Describing the atrocities that fascists would commit is easy but unless you are willing to assign a philosophy and agenda, the story falls flat. The people described exist already but not because Fox created them.
The patriots protesting in favor of the confederate flag, confederate monuments, against women's rights, against pro-environmental regulation and whatever pro-human topic offends them, self-identify as white nationalist, Nazis and white supremacists. They wear their red hats and drape in U.S. flags and funny enough MAGA hats have been showing up overseas, worn by Nazis and other white supremacists in places where Nazi flags and insignia are illegal. For the story to make sense, a little courage is needed. Creating a false equivalency between the above and "liberals" is weak analysis and leads to weak writing.
The Nazis in Germany and Fascists in Italy and Spain were not a majority and they were not successfully opposed by their enemies but more importantly they were supported by prevailing cultural "truths" that the majority wouldn't reject. As a result, Jews were burned, labor organizers were hung, gypsies died in concentration camps, and all the rest. 5% won't cause the civil war, the quiet support of millions of people afraid to oppose their positions or who agree with them (but are "good" people) could. Based on real world circumstances (Spanish Civil War, North American slavery, rise of the fascists in Europe and the US today), the story would have much more plausibility and some emotional heft.
Their opponents watch MSNBC and are ready to mobilize into liberty brigades or some such. MSNBC doesn't create activists but does create a population segment who can and do applaud their own progressive views. Actually doing something about them or with them, not so much. MSNBC actually purged its lineup of people who were a little too loud or reminded viewers that the stories reported, had real world consequences for the victims and a few tears might not be the appropriate response.
That diametrically opposed progressive population segment isn't unified, organized or motivated enough to flood congressional email accounts with policy questions. "These are not the social warriors that you are looking for. Move along." The one side has zero people prepared to even defend themselves and the other side is hoping for an opportunity to shine. GED with assault rifle wins against J.D., PhD and Masters degrees armed with self-congratulatory outrage again, folks.
Half of the established defenders (military, police) of the flawed democracy, (writer's description, not mine) which has always moved towards human improvement???, rebel against their country.
Centuries of land slavery, civil rights accorded to the descendants of slaves only took 90 more years because those descendants fought and sometimes died for them, 60 years after that (The Present) black college graduates earn on average less than white males with a HS diploma. Then there's the suppression of women's voting rights, The supreme court's quashing the ability of women to file class actions against corporations (anyone really) and the pending repeal of abortion rights. Latinos have now been recorded being accosted on the street while working for proof of citizenship by whites who don't even need a uniform and who suffer no legal consequences afterward. The above are unpleasant but no one denies that they are on the internet or in libraries.
Half of the defenders of those laws and that legal tradition betray their oaths, no way. Just because a military officer looks the other way when a subordinate once again, unfairly punishes a black or Latino soldier, sailor or airman doesn't suggest that they would join white nationalists to restore the freedom of ??? to ??? against ??? Just because a police officer corroborated a fellow officer's lies during a murder investigation into the shooting of an unarmed Black, Brown or Asian teen/child/woman/pensioner/junior partner/bus driver doesn't indicate that he might join with white nationalist patriots in taking back??? their country.
With that backdrop, it's impossible to blame 90% of apathetic voters as the setup for the story. The writer used 80% vs 10% actively engaged with Fox and MSNBC but the reality is much more likely that network executives would throw parties if either network has that high a percentage of viewers.
There are believable fascist thugs but other than being poor and stupid or middle aged, middle class officers of those thugs (for the power trip, the rape camps or general machismo?), there's nothing to explain what their origins are or what their expected payoff for treason is? The liberals are hopeless but armed and proficient with assault weapons, familiar with military room clearance and have a network of like minded fellows to join for anti-coup operations.
The original idea was good but starting with the flimsy premise and the inadequate social analysis the book fell apart. From the next book on, it will be another typical apocalypse story minus the "let's shoot all the dangerous criminal non-whites", "drive away or kill any non-christians" and the obligatory "let's put our American flag on the roof, because this is a shining city on the hill" (I love that last one, spoken by President Reagan after running on a campaign of reining in "black bucks and welfare queens"). I like this writer's other books but this book didn't do it.