The main reason Democrats lost in 2010, after such big wins in 2008, is because a group of Democratic strategists and leaders (and maybe including president Obama himself) concluded that it was a good idea to alienate the Liberal base. After 2008, Democrats got arrogant, they decided it was good strategy to govern from the status-quo, change-little, "center", to capture independent voters, under the assumption that the base will follow no matter what, like cattle, under the argument that the alternative, GOP would be worst. That strategy was a mistake, a bet that didn't pay off. Obama and Democratic leaders made it a quasi habit the "sticking it" to the Liberal base and then wearing that as batch of honor in front of Republicans and independents.
Also, you cannot promise big changes, boldness and then deliver middle of the road, half baked solutions that change little while lack boldness. Even independent voters understand that sometimes big changes are necessary and boldness is warranted. With the crisis that Obama inherited, it would have been much easier to explain to independent voters the reasons for boldness than trying to explain the lack of it. Liberals were ready an anxious to engage in that battle and Republicans offered the perfect ammunition all the way with their obstruction, lack of ideas and the extremism of their Tea Party faction. However, that became very difficult when the policies left to defend were just the same status-quo that change-little and made Wall Street richer, while made Main Street poorer.
But that is the past now. November 2, 2010 was a bad day for Democrats, but it actually was a victory for Liberals. Now Obama and Democrats know that Liberals are willing to let the Democratic Party lose. Now Obama and Democrats will think their policies twice and I am sure they will not wear the "sticking it to the Liberal base" as a batch of honor anymore. Not if they are smart.
This is the moment for the Liberal movement to push the Democratic Party to become the agent of change that the American people expected of them when they voted in 2008. This is the moment for the Democratic Party to listen, "man up" and act accordingly.
Liberals let Democrats lose in 2010 and we will let them lose again in 2012, unless we see that "Change We Can Believe In!"