Sure, after the other four listed. Who would be further left than him other than FDR, Truman, LBJ, and Kennedy?
Since TR, Eisenhower and Nixon were all more left-wing than him, I'm surprised at your choice.
I think that's debatable, and in any case those men were right-of-center in their times, which is no recommendation of their character (in fact I find both TR and Nixon a bit distasteful, but Eisenhower it is true was very acceptable for a Republican). I think Obama's inclinations are to the left of an Eisenhower, he is just trapped by the horrible new ultra-right reality of american government.
