And was it Harry White, who was an actual socialist/marxist, as FDR’s VP for awhile?
Alger Hiss, Harry Hopkins -- there were plenty whom many have wondered about vis-a-vis their true loyalties. For Alger Hiss of course there is no doubt that he was a Soviet stooge.
Lots of Soviet sympathizers in the FDR administration. Yes both countries were fighting Nazis but..
the notorious Sedition Trial of 1944 was where FDR's DoJ targeted Soviet communism's critics.
Once the war started the debate switched to post-war. Many were wary of Stalin -- if they were too outspoken (and not members of the Congress) they risked charges of sedition.
The judge soon tired of DoJ's shenanigans and stopped the trial. Though freed the defendants paid a heavy price nevertheless.