You can make the argument either way. Many of his closest advisers WERE card carrying Communists.
People will never agree about all the details, but here’s one comment I just found on the web, which pretty much sums up what I have read elsewhere:
“When his Chief of Security Berle brought him information from the Communist courier Whittaker Chambers that there were 2 Soviet spy rings at the highest levels of his administration, naming names like Hiss, White and Silvermaster, FDR told him to “go jump in a lake.” The report was suppressed for years. The KGB archives list 221 agents in the most sensitive sections of the Roosevelt administration in April 1941. There were probably a like number of Soviet military GRU agents.”
Even if he was sympathetic to them, FDR was not a commie. My suspicion, for which I have no proof, is that he looked upon the pinkos as useful idiots.
FDR became a man and a politician during the progressive era. He was a NY state politician who cut his cloth by opposing Tammany, which in those days made one a “reformer” but not a republican. Even while his cousin, Teddy Roosevelt, ran for president in 1912, FDR stayed democratic, principally, I believe, as a means of maintaining a political edge.
Meanwhile, he came to believe in the Wilson WWI centralized economy, and he refused to admit of its failures. When he took office in ‘33, it was to Wilson’s WWI schemes that he immediately turned: wage/price controls, government control of labor disputes, and government allocation of resources. As a progressive, and throughout his term of office, his policies promoted big business at the expense of small business.
As a progressive, he blamed all ills on competition and consumerism. He believed that credit was the source of all 1930s evil and that competitive forces would ruin the earth.
He was a fool. But he was not a communist. His goal was to nationalize the economy without taking ownership over it. If there’s any system akin to it, it’s called national socialism. The progressives taught him how.