This was a very inferior remake of "Seven Days in May".
What dooms it from the outset was Jason Robards' characterization of General Lloyd (Scott). It is central to the credibility of the plot that this is a knife fight between an unpopular dovish president whom most of the country fears has endangered America by his disarmament treaty and his charismatic hawkish Chairman of the Joint Chiefs of Staff. In the original "Seven Days in May" General Scott is a national war hero whom millions of Americans idolize and who, if the election were held today, would win in a landslide. Jimmy Carter vs Douglas MacArthur. For the concept of a military coup to be credible there has to be a national security crisis pitting an unusually weak president against an unusually powerful general.
The original "Seven Days in May" had Burt Lancaster, an actor of enormous virile magnetism playing General Scott. You can see him as the kind of heroic man on horseback a frightened nation would turn to for salvation. You can see him as the kind of man who could seduce a nation into "Well, why don't we set aside the Constitution just this once. I won't tell if you won't tell."
This film's General Lloyd was a charisma-challenged snarling fascist whom no one would follow off a sinking ship. It is impossible to imagine him commanding the support of millions of Americans which is what you would have to do if you plan on ruling the country after shooting your way into the White House.