“Capitalism is doomed and is not worth trying to save,” he exhorted the flock in February 1934, calling it a “Siamese twin” of Marxist socialism. In November of that year, Coughlin announced he was forming a new group called the National Union for Social Justice. This independent organization would be based upon “16 Principles” identified by its founder—including abolition of the Federal Reserve, simplification of government, and liberty of conscience. The aim of the group, said Coughlin, was to “drive out of public life” those who had betrayed these principles and broken their promises to the people. He boasted that the union would soon recruit five million members.

Coughlin’s first opportunity to flex his new political muscle came just a few months later. In January 1935, Roosevelt sent a long-delayed treaty to the heavily Democratic Senate, which would make the United States a participant in the World Court. The administration was confident of gaining ratification. Less than forty-eight hours before the vote, however, Coughlin took to the air to denounce the treaty as an affront to American sovereignty. In a voice filled with manly indignation, he urged his listeners to “keep America safe for Americans and not the hunting grounds for international plutocrats!”

Within hours of Coughlin’s broadcast, tens of thousands of telegrams flooded the Senate, and the treaty was rejected by a wide margin. “I regard this a decisive defeat of the administration,” Harold Ickes, Roosevelt’s Secretary of the Interior, recorded in his diary of the vote. One Democratic party official warned that Coughlin had become “a bigger menace to the President and our government than ever.” The Fighting Priest, of course, was jubilant.

But through the rest of 1935, Coughlin had trouble replicating his success on the World Court vote. His audience had never been larger, and his radio network had grown to twenty-eight stations covering every major city in the Midwest and Northeast (as a Catholic, Coughlin’s influence was always limited in the heavily Protestant South). He maintained his own full-time lobbyist in D.C. Nevertheless, Coughlin’s assaults on the Federal Reserve, the gold standard, and his support for a bonus bill for war veterans were all stymied through deft political maneuvering by Roosevelt and his allies on Capitol Hill.

Though Coughlin would repeatedly deny it, it seems clear that he had harbored some idea of the National Union as a potential third party in American politics from its inception. In typical apocalyptic fashion, he had been forecasting the demise of the two-party system for some time, telling Collier’s Magazine he thought both parties would disappear within a decade.

Seeking to fill this impending political vacuum, Coughlin embarked on a speaking tour that he hoped would recruit millions of new members for the National Union. Those who attended his thunderous rallies came away impressed by the passionate devotion of the crowd. And at first, Coughlin had some modest success. In 1936, candidates endorsed by the National Union won congressional primaries in several large states, including Michigan, Ohio, and New York.

Coughlin never believed that a third-party candidate could directly challenge Roosevelt. Yet he was convinced that the millions of voters organized under the National Union banner could weaken FDR and potentially put a Republican in the White House. As the 1936 election approached, Coughlin joined forces with the remnants of Long’s organization (the Louisiana senator had been murdered in the summer of 1935) and other third-party splinter groups to form the Union Party, which chose North Dakota Congressman William Lemke as its presidential candidate.

At the party’s convention in August, Coughlin stripped away whatever had been left of his relationship with Roosevelt, literally peeling off his vestments during a stem-winding speech that labeled FDR as the “great betrayer” and a “liar.” On the stump, Coughlin was even more graphic, telling supporters that “when an upstart dictator in the United States succeeds in making this a one-party form of government, when the ballot is useless, I shall have the courage to stand up and advocate the use of bullets.” The priest swore that if he could not deliver nine million votes for Lemke, he would retire from the radio.

Douglas McCollam is a contributing editor to CJR.