I always thought the problem was with those who combined Marx's writings with Leninism, hence the label Marxist-Leninist.

Marx's contribution was to describe a socio-economic model that would be better than what he saw. Lenin's part was to prescribe a revolutionary vanguard, who knew the 'right' way in everything and would achieve socialism.

You can be a socialist without being a Marxist, a Marxist-Leninist or a Leninist.

Somehow I have m' doubts President Obama has any of those labels, but then I'm a pesky "limey".