As his rage becomes more intense, Donald Trump's words increasingly resemble the anti-Semitic ravings of Father Coughlin. Both men exploited the latest technology to foment ancient fears. The Radio Priest failed. So will Mr. Trump.

Charles Edward Coughlin was Canada's unhappiest export to the United States. Born in Hamilton and ordained in Toronto, he moved to Detroit in the 1920s, where he established a parish in the new suburb of Royal Oak.

Coughlin loathed communists for their godlessness, and capitalists for oppressing the working man. And he loathed Jews, who he believed were to blame for both evils.

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He was among the first to grasp the persuasive power of the new technology of radio, using it to broadcast sermons so mesmerizing that, in the depth of the Depression, a quarter of the U.S. population tuned in to his broadcasts every Sunday at 4 p.m.

"You forgot there was a Depression," one listener later recalled. "You forgot that you had to stand in line to get your food."

Coughlin spoke for "our dispossessed farmer, our disconsolate labourers, who are being crushed at this moment while the spirit of internationalism runs rampant in the corridors of the Capitol."

He claimed infallible knowledge. "I know the pulse of the people," he declared. "I know it better than all your newspaper men. I know it better than do all your industrialists with your paid-for advice."

At first, he thinly disguised his anti-Semitism by referring to "international bankers." But as the Depression lengthened and fascism rose in Europe, he dropped the codewords. "When we get through with the Jews in America, they'll think the treatment they received in Germany was nothing," he vowed in the 1930s.

Although tens of millions listened, tens of millions more turned away. His efforts to influence the 1936 election went nowhere. When the German fascists he so admired declared war on the United States, Coughlin went silent, and was never heard from again outside his parish.

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Today, he is virtually forgotten. But at a dangerous hour, Charles Coughlin inspired many and terrified many more. And the Republican candidate for president increasingly echoes him.

Last Thursday in Florida, Mr. Trump delivered a speech that was pure Coughlin. He spoke of "the economic decisions that have robbed our working class, stripped our country of its wealth, and put that money into the hands of large corporations and political entities."

He claimed his Democratic opponent, Hillary Clinton, "meets in secret with international banks to plot the destruction of U.S. sovereignty."

And he declared his campaign to be nothing less than a struggle to determine "whether we're a free nation, or whether we have only an illusion of democracy but are in fact controlled by a small handful of special global interests."

Some may claim that Mr. Trump's Coughlinesque invocation of "international banks" and "special global interests" means something other than "international Jewish conspiracy." But we're all grown-ups here. We know what's going on.

He repeated much of this later through his favourite social media venue, Twitter, including the classic anti-Semitic claim of a conspiracy against him "by the dishonest and distorted media."

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None of this is new. Economic insecurity stalks some of the last enclaves of white, working-class America, stoking fears of racial decline that are as old as the republic itself: The Alien and Sedition Acts of 1798, the Know-Nothings of the 1850s, the Chinese Exclusion Act of 1882, the Espionage and Sedition acts of the First World War, the Japanese internment during the Second World War, the John Birch Society. Each has flourished in its time, but ultimately disappeared, as will the alt right.

Now, some of the last of the old stock have turned for salvation to Mr. Trump, who already blames Mexicans and Muslims for their troubles, and who is now dog-whistling a Jewish conspiracy. But this never works in the end.

It may seem hard to imagine, but Donald Trump may one day be as obscure a footnote as the Radio Priest.