Harry Turtledove, Joe Steele. ROC, 2015
Alternate history: Stalin's parents emigrate to the US, and he's born here rather than in the Tsarist Empire. He changes his name to "Steele" rather than the Russian equivalent.
He gets the 1932 Democratic Presidential nomination, after Franklin Roosevelt's unfortunate death. Wins the election, stays President till his death.
After an interval in which it looks like the US will stop being a dictatorship, a worse man takes over: J. Edgar Hoover.
Do I recommend it? If you're a history buff or a political junkie, yes. Otherwise, worth a look to see if you want to continue reading.