Holy shit, that wiki plot synopsis

Iowa Senator Jim MacVeagh is summoned to Camp David by US President Mark Hollenbach. MacVeagh, who is expected to become Hollenbach’s next Vice President, becomes concerned because Hollenbach shows signs of intense paranoia. He erratically expresses his desire to develop a closer relationship between the United States and the Soviet Union, and attempts to cut ties with US allies in Europe. Hollenbach believes the US news media are conspiring against him. MacVeagh is the only person who notices that Hollenbach’s mind is crumbling, as the presidential advisors and politicians he attempts to warn ignore him. The sole person in possession of evidence of Hollenbach’s mental decline is his mistress, Rita. Hollenbach puts both MacVeagh and Rita under an FBI investigation.

Anybody reading this should guess when you think this book was written.