Here's some third party info on Father Coughlin, and the free speech/ political battle between him and FDR's folks (a battle Coughlin lost).
During his peak, Father Charles Coughlin was considered the undisputed king of talk radio. And whether a fan of Coughlin’s or one of the many denouncers of his "brand" of social justice, he continued to systematically etch his place into the fabric of American culture. His show began in the mid 1920s and peaked during the early 1930s. At the time, his broadcasts were one of the most popular in the country, drawing in millions of viewers and receiving upwards of 80,000 letters per week.
The first outspoken voice against Coughlin came from a fellow holy-man. The Reverend Walton E. Cole, a minister in Ohio, urged the Roman Catholic Church to remove Coughlin and his seditious broadcasts from the air. Father Coughlin’s personal attacks on Roosevelt, industrialism, and the Jewish people worked to have him shunned by many priests and pastors of the era, though Coughlin’s show still remained on the air with a heavy base.
When this approach didn’t work, the Roosevelt administration declared that the First Amendment’s free speech didn’t cover radio broadcasts, and Coughlin was promptly forced from the air when he was unable to receive a newly mandatory operating permit. Coughlin’s counter to this was to purchase independent air time and play prerecorded shows on the air.
In 1939, the Code Committee of the National Association of Broadcasters forged new rules and placed increasingly rigid limitations on the sale of radio time to controversial spokesmen. This was directly aimed at Father Coughlin and his unwillingness to concede his throne as the nation’s top dissenting voice. Now, manuscripts would have to be given in advance, and stations were threatened with a loss of license should they not comply with the new standards on "free speech." In a 1939 issue of Social Justice, Coughlin stated that he had been forced off the air by those who controlled circumstances beyond his reach.
Even though the government – the very entity put in place of guarding free speech – found a loophole to destroy it, Coughlin estimated that the written word was still "untouchable." He then started to heavily print uncensored editorials in his newspaper. In a relentless game of cat-and-mouse, the Roosevelt administration stepped in again removing Father Coughlin’s mailing rights and making it impossible for his papers to reach their destinations. The administration cited that Coughlin could print whatever he wanted, but did not have the right to use the United States Post Office Department to send his publications.
Soon after, Coughlin found his influence was greatly reduced. The world quickly began to change around Coughlin, and he was now considered a true enemy of the state for his isolationist ways and sympathetic leanings toward the enemy. He was ordered to stop his political activities and take over the duties of parish priest at the Shrine of the Little Flower. Coughlin retired in 1966 and continued to write anti-communist papers until his death in 1979.