From Elliot A. Rosen's *The Republican Party in the Age of Roosevelt: Sources of Anti-Government Conservatism in the United States* (University of Virginia Press 2014), p. 9:
"As the Democratic Party's National Convention opened on June 28, 1932, Herbert Hoover broached the issue of his likely opponent with his press secretary, Theodore Joslin. 'Do you think Roosevelt will be nominated?' the president inquired. Joslin assured him that the governor of New York would overcome his projected one-hundred-vote deficit on an early ballot. Less sanguine about Franklin D. Roosevelt's chances, Hoover noted: 'I am afraid of Baker. . . . He's a strong second choice of the convention and would be a harder man for me to beat.' The strength of Ohio's Newton D. Baker depended on his reputation for eloquence, intelligence, and probity. Woodrow Wilson's secretary of war, Joslin conceded, would succeed if Roosevelt lost momentum by the fourth or fifth ballot. There seemed 'one way to nail him [Baker]. [William Randolph] Hearst hates him,' Joslin said, referring to the newspaper magnate's abhorrence of Baker's internationalist views.
"Joslin suggested a telephone call by the Hoover aide Lawrence Richey to Louis B. Mayer, vice president of Metro-Goldwyn-Mayer and vice chairman of the California State Republican Central Committee. Mayer would be asked to warn the isolationist Hearst against the growing likelihood of a Baker nomination. The notion of selecting the weaker of Hoover's two potential opponents in the coming campaign sounded appealing, and the call was made. Hoover exulted: the scheme worked 'to perfection.' 'If Baker isn't stopped, it will not be the fault of Hearst.'"
https://books.google.com/books?id=KWn5AQAAQBAJ&pg=PP25
So without Herbert Hoover's intervention, would FDR have lost the nomination to Baker? I doubt it. I don't think Hearst needed a phone call by Mayer to remind him how much he hated Baker. (Rosen himself says "This is not to suggest that Herbert Hoover had a hand in the choice of his adversary...but rather to shed light on his strategy.") Still, it is interesting how Hoover thought Baker would be a stronger opponent, apparently subscribing to the widespread view (popularized by Walter Lippmann) of FDR as a "Boy Scout" or "country squire"--shallow, eager to please everyone, with few real convictions, etc. In short, someone too lacking in *gravitas* for the American people to turn to in an hour of crisis like this--or so at least Hoover hoped. If nothing else, this is another example of how maneuvering to get the other party to nominate a weak candidate can backfire--as in the case of Pat Brown leaking unfavorable information about San Francisco Mayor George Christopher in 1966, because Christopher would be harder to beat than the actor and "extremist" Ronald Reagan...