The early 20th Century was a turbulent period of time around the world. Tsarist Russia was overthrown by a socialist revolution; various colonial outposts were faltering and the United States economy fell into a deep depression. Herbert Hoover, the Republican president who oversaw the economic meltdown, felt that the economy could recover on its own. When that didn't happen, voters swept him out of office, electing Franklin Delano Roosevelt.
Roosevelt enacted a sweeping set of laws to establish a safety net for Americans. The idea was to stabilize the economy and prevent the sort of revolutions seen overseas. To the wealthy, this was tantamount to communism. Instead of seeing the benefit of stabilizing the economy and thus preventing the working class from rising up against them, a cabal of wealthy financiers and industrialists began talking about staging a quiet coup to replace FDR with someone who would roll back his reforms and policies.
The alleged plan, known as "The Business Plot" was exposed by the man who claimed he had been brought in to lead it- Major General Smedley Butler, who testified that he was brought into the plot because he had switched his political affiliation from Republican to Democrat and thus would not be suspected of supporting such a plot.
One of the alleged conspirators was Prescott Bush, who would ironically be the father and grandfather of two future presidents. At the time, the elder Bush was merely a wealthy banker, though he would later insert himself into the world of politics. A congressional committee was convened, but unlike the later hearings into alleged communist ties, none of these conspirators were ever called before the commission, nor were the accusations heavily publicized. Some newspapers even labeled it a hoax.
In any case, World War II intervened and the case dropped out of the public eye. Smedley Butler passed away in 1940 at the relatively young age of 58. After the war, the country's attention turned to hunting communists, and the conservatives who fought against the New Deal were only too eager to shift the spotlight of scrutiny elsewhere.