This is the problem that Yuri Bezmenov referred to when he said that the leftist ideologues and academics would be the first ones eliminated in any Communist purges. Obama is running up against the same thing right now.
The disillusion has produced a growing tide of organizing energy — and money — among liberals aimed at dragging the White House back to where many supporters believe Obama's heart really lies. Union presidents have discarded their talking points and are openly sparring with the White House, while gay rights activists threaten civil disobedience, the ACLU keeps litigating, and congressional Hispanic leaders work to force their issues into the debate.
But while those actions may actually create politically useful space to the president’s left, the other consequence of disillusion is what polls have found to be deepening apathy among Democratic voters.