The National Journal says yes. Is this true? In this February post, guest blogger Sarah Binder noted that the National Journal relies on a selective set of roll call votes and does not take into account absences. A better measure is the ideological score computed by Keith Poole and Howard Rosenthal (a.k.a. NOMINATE scores). Here is their analysis of where Obama, Clinton, and others fall on the NOMINATE scale. I reprint a couple of their key graphs below:
Obama is not the most liberal Senator. He is just slightly to the left of the average Democrat.