They are not Marxists. According to historical tests, they are utopian fascists who use political correctness to harass people and justify violence.
Know your enemy or you will not be able to defeat them.
A primer on Obama and his movement:
Barrack Obama: The Quintessential Fascist:
http://www.americanthinker.com/2009/05/barack_obama_the_quintessentia_1.html
There is nothing at all proletarian about Obama.
You need a dictator to make Marxism work. People must be forced against their own benefit.