Steven Malanga writes an in—depth analysis in City Journal of the real source of money and organization power on the left: the public employees and their unions and allies. The article is long, colorful, and insightful. Here is a fair use excerpt to give you some flavor:

Perhaps it's not surprising that the urban Left has evolved into so narrow a movement, promoting no more than its own self—interest. Though it started out as a romantic, if wrongheaded, idea, the War on Poverty was the child of idealists who really believed that a benevolent, paternalistic government could offer solutions that America's private economy couldn't provide for the poor. But the most cherished ideals and programs of the movement have turned out to be demonstrably wrong, and many Americans now reject them.

....the new urban Left has emerged as an increasingly cynical coalition ever more focused on goals that benefit its members and their allies, even though it retains the jargon of 'social justice.' The living—wage movement is largely the work of unions more interested in laws that bolster union membership and derail privatization or productivity—boosting measures than in legislation that genuinely helps the poor. Many of the living—wage laws enacted around the country exempt unionized companies from adhering to wage guidelines

.... by donning the mantle of 'social justice' and invoking the liberation language of the 1960s—for example, in its campaigns to win domestic—partner benefits for municipal workers—the New New Left has managed to dupe a generation of celebrity liberals, idealistic young voters, and religious leaders who have become their allies in the Blue—state coalition.

Thomas Lifson   5 18 06