Equating the two with Karl Marx would be appropriate enough but too predictable. I'm going with the other Marx on this one: Groucho.
I'm old-school enough to know who Groucho Marx is (grew up watching "You Bet Your Life" when it still came on television), so I love this photo comparison of Groucho and Keith Olbermann.
Also worth a watch is this video of Obama. Set to a song from the Marx brothers' 1933 film, Duck Soup, which lampooned authoritarian governments (it was banned by Mussolini), it's both funny and depressing at once.
Get through the first few seconds of the soprano chick, and the rest is spot on.