It’s just not true. Electing more Democrats who are anti-choice won’t do anything to stop confirmation of people like Alito. Electing more Democrats who are too afraid to act on their principals won’t do anything. Principled leadership can work, and must work, if we hope to stop the steamrolling of individual rights being engineered by the right.
What liberals (or progressives, if you insist on letting them define you) need to do is start supporting candidates who actually hold progressive beliefs. The parties and the special interests love the current system–the one Neil proposes–where we are beholden to the parties and interests. The only way to break from that mindset is to start demanding results, and to stop settling for compromises that make them marginally better than the other side.
Is the answer really continuing to support people like Joe Lieberman?