It's difficult to say.
Tell me if the following politicians are what you'd call to Obama's left or right.
Andrew Cuomo
Martin O'Malley
Brian Schweitzer
...It really gets hard, doesn't it?
Cuomo is to Obama's right on most issues but there are of course exceptions. Economically he's too right-wing for me to consider supporting in a primary. O'Malley strikes me as quite similar to Obama but I could be missing something. Schweitzer is for the most part substantively to the left of Obama except on those issues that someone in Montana specifically has to pander on but with an odd Western populist-libertarian streak that makes him hard to pin down stylistically. I really like Schweitzer.
...You're right, this is hard.