I agree that FDR was not a communist. But he was almost held hostage in the White House by communists. His wife was a Red:
"Smearing good people like Alger Hiss and Lauchlin Currie is, I think, unforgivable...Anyone knowing either Mr. Currie or Mr. Hiss, who are two people whom I happen to know fairly well, would not need any denial on their part to know they are not Communists. Their records prove it."--Eleanor Roosevelt. August 16, 1948
Alger Hiss, who traveled with FDR to Yalta where Eastern Europe was handed over to the Soviets was an officer in the KGB.
Laughlin Currie, special advisor to Roosevelt, who helped Mao gain power, lived in the White House down the hall from FDR's quarters. Currie fled the country in 1948 rather than testify before Congress.
Harry Hopkins, who also lived in the White House, was--at best--a deep shade of pink.
Assistant Treasury Secretary Harry Dexter White, who cut off money to the Nationalists allowing Mao to gain power and whose supported turning Germany into a pasture after WWII so the Red Army could roll to the English channel, was a KGB agent.
FDR's mistress Lucy Mercer was as left wing as Eleanor.
Owen Lattimore,Roosevelt's key advisor on China, followed the Soviet line on virtually every foreign policy issue. During the Moscow show trials, Lattimore declared they "sounded like democracy to me." After the war, he advocated the withdrawal of American troops from Japan and Korea.
Henry Wallace, FDR's VP, toured Soviet concentration camps with Lattimore and said nothing when Lattimore compared the gulags to the American TVA.