Absolutely. His mother was very likely a marxist, she married 2 marxists, one of whom raised him for his formative years, he was mentored in high school by a soviet stooge marxist, in college he "sought out the marxist professors" according to his own autobiography, and once out of college and on his own, his best friend and sponsor is Wm. Ayers, and he applies the theory of an avowed Marxist, Saul Alinsky, who he knows so well he teaches about.
Yeah, it's beyond the pale to call him a Marxist.
Oh, and then look at his policies. They are all either Marxist or advance the cause as far as he can in this society.