On October 23, 1944, a feverish Orson Welles, laid up at the Waldorf-Astoria Hotel in New York City, received a telegram from the White House. “I have just learned that you are ill and I hope much you will follow your doctor’s orders,” read the message from President Franklin Delano Roosevelt. “The most important thing is for you to get well and be around for the last days of the campaign.”

For more than a month, the 29-year-old actor and filmmaker had been traveling the United States, making speeches on behalf of the 62-year-old president. Roosevelt was seeking an unprecedented fourth term, hoping to lead the country through the end of World War II. But as American soldiers and sailors advanced toward Germany and Japan, Republican opponent Thomas Dewey’s questions about the president’s age and energy began to resonate with the public.

Roosevelt was campaigning hard, trying to counter the concerns about his health, but he needed surrogates. None— including the many Hollywood stars who gave an occasional speech for Roosevelt in 1944—were as passionate and dedicated as Welles. His famous, resonant voice was associated with the gravity of epic conflicts, from Shakespearean tragedy to Martian invasion, for his contemporaries. And in response to the president’s plea, Welles prepared for real-life political war.

Two days after the president’s telegram, his fever broken, Welles cabled the White House. “Dear Mr. President: This illness was the blackest of misfortunes for me because it stole away so many days from the campaign,” he wrote. He credited Roosevelt’s telegram for inspiring him to rally and promised to get back on the road: “This is the most important work I could ever engage in.” Two days later, back on his feet, Welles gave a ten-minute campaign speech for Roosevelt on the CBS Radio Network.

Throughout fall 1944, Welles made campaigning for Roosevelt his full-time job, leaving his pregnant wife, actress Rita Hayworth, at home to travel the country by plane and train. In his speeches to rallies and Democratic clubs, Welles attacked Republicans as plutocratic elitists with the same withering contempt he’d aimed at newspaper baron William Randolph Hearst in his epic 1941 debut as a film director, Citizen Kane.

Welles’ left-wing politics made him sympathetic to Roosevelt’s New Deal. He’d already worked for the U.S. government’s Federal Theatre Project, staging “Macbeth” with an all-black cast in 1936, and broadcasted on behalf of a Treasury Department war bond drive earlier in 1944. And even after Roosevelt disappointed progressives by replacing radical-leaning Vice-President Henry Wallace with Missouri moderate Harry Truman on the 1944 ticket, Welles remained loyal. He introduced Wallace (who agreed to campaign for Roosevelt even after he was ditched for Truman) at a Madison Square Garden rally on September 21. Warming up the crowd, Welles attacked Republicans as “the partisans of privilege, the champions of monopoly, the old opponents of liberty, the determined adversaries of the small business and the small farm.” He even called out Hearst, his archenemy, whose newspapers supported Dewey.

Throughout 1944, Welles often met with Roosevelt at the White House and on the president’s campaign train. According to biographers, the actor also sent the president ideas for his speeches—suggestions the president included in his addresses. Decades later, Welles even claimed to have helped Roosevelt come up with one of the most memorable lines of the 1944 election: the punch line of a speech concerning a political fracas over the president’s dog.

The speech was a huge hit, and the Welles-penned joke was the main attraction. “[FDR] loved it,” Welles told a biographer in 1985, “and he asked me afterwards, ‘How did I do? Was my timing right?’ Just like an actor!”

FDR also figures in a curious anecdote mentioned in several Welles biographies— and in the FBI’s file on the actor’s 1940s political activities. In August 1944, gossip columnist Hedda Hopper reported that Roosevelt had called Hayworth to let her know that Welles would be away from home, engaged in special work for him. According to Frank Brady’s biography Citizen Welles, the president called Hayworth when Welles balked at his request. “But Mr. President, Rita will never believe me if I can’t tell her where I am,” Welles said, according to Brady’s book.

Hopper, suspecting infidelity when Hayworth told her about Welles’ absence, grilled Hayworth until she mentioned Roosevelt’s phone call, then reported it in her column the next day. The FBI dispatched an agent to interview Hopper. She “stated she did not know exactly what the President was having Welles do,” reads the agent’s report, “but she did know that he was on some kind of mission for the President.”

Welles biographers disagree on what the mission might have been. Brady, recounting a story Welles told him about shooting footage of Albert Einstein talking about the theory of relativity, suggests Welles may have been working on a never-released documentary project about the atomic bomb.

As the election neared, Roosevelt’s campaign turned to Welles, a radio veteran famed for his terrifying October 1938 broadcast of “The War of the Worlds,” for high-profile speeches. On October 18, 1944, a few days before he fell ill, Welles appeared on the same radio program as Roosevelt’s rival, Dewey. On the air, Welles accused Republicans of running “an energetic campaign of vilification” against Roosevelt, but insisted that history would vindicate him. “I think that even most Republicans are resigned to it,” Welles said, “that when the elections are over and the history books are written, our president will emerge as one of the great names in one of democracy’s great centuries.”

After recovering from his illness, Welles accompanied Roosevelt to a rally in Boston’s Fenway Park, where Frank Sinatra sang “America the Beautiful” to his usual cheers from teen girls. “The crowd roared its enthusiasm as Orson Welles and Frank Sinatra were introduced,” reported the Boston Globe, which referred to the two stars as “the ‘dramatic voice’ and ‘The Voice.’”

Welles, his anti-elite rhetoric as sharp as ever, claimed that the Republicans were running an entirely negative campaign. “By free enterprise they want exclusive right to freedom,” he argued. “They are stupid enough to think that a few can enjoy prosperity at the expense of the rest.” Welles kept campaigning up to election eve, when he delivered a nationally broadcast radio speech on a Democratic National Committee program.

Impressed with Welles’ oratory, Roosevelt suggested that the actor might have a future in politics. Welles, who had ambitions of running for office, was delighted. He would later tell people that, encouraged by Roosevelt, he’d contemplated running against U.S. Senator Joe McCarthy in his native Wisconsin in 1946.

Roosevelt may have been flattering, but some biographers have another take. They characterize Welles’ senatorial daydreams of 1944 as a sign of vanity, and his eloquence on Roosevelt’s behalf as too high-minded to succeed from the mouth of a candidate himself. “He was devout about great times needing great men,” wrote David Thomson in Rosebud: The Story of Orson Welles. “So he missed that drab, sly, common touch that gets elected.”

Still, Roosevelt appreciated Welles’ oratory, and the connections between theatrical and political performance. After the election, in which Roosevelt beat Dewey 53 percent to 46 percent in the popular vote and 432-99 in the electoral vote, Roosevelt met with Welles once more. He also sent Welles another telegram, thanking him for his help with the campaign. “It was a great show,” Roosevelt cabled, “in which you played a great part.”