The fundamental problem among the left is that we do not have strong institutions the way that the right has.

They have:
Conservative Talk Radio
Well Funded Think Tanks
Fox News and the Corporate Media
Evangelical Churches with multi million dollar operations
Corporate Dollars

We have:
Air America Radio
Academics dispersed among campuses
No Progressive TV
Disperse Buddhists, Quakers, UCC, Jews, some Catholics
Declining Unions

Union members voted by a 2 to 1 margin for John Kerry.  While there are some demographic reasons for this (Union members are more likely to be women and people of color), the real reason is that the institution regularly frame their conversations around bosses trying to get over on workers and how workers need to fight back.

Whether it is a contract enforcement issue, or an union organizing campaign, legislative or electoral fight, unions talk to their members about how the boss is screwing them and how we need to fight back.
If you overlayed unionization rates among the red states and the blue states, you will see that there is a direct correlation.  The redder the state, the lower the unionization rate.
My own union, SEIU has over 50% of our 1.8 million members living in either NY or California.

Organized labor must grow again if we are to revive progressivism in this country.

Over the next few months, organized labor will be engaged in an internal battle over the direction of the AFL-CIO.
SEIU President Andy Stern is leading a charge to restructure unions.
Basically, the AFL-CIO is a loose confederation of unions where any one affiliate can pretty much do whatever they want.
You can check out more on these issues in this internal fight at http://unitetowin.org

Organized labor has to be revived as it is the only force able to provide a check on corporate power.