Under normal circumstances, when a party "loses" an election, the base is the strongest and sometimes the only constituency standing within the party. We saw this clearly when republicans lost big in 2008. Only the republican base was left and GOP's first task was to rebuild that base.
So equally, under normal circumstances, if Democrats "lose" the Nov. 2 election, the Liberal base will be the strongest constituency standing within the Democratic Party and the party's first task in getting ready for 2012 is to make amends with its Liberal base.
But that is under the "losing" scenario. What would happen if Democrats do not "lose", which at this moment means keeping at least one chamber of Congress? How Progressives will be the strongest constituency within the party if the party didn't "lose"? The answer is because of the process that resulted in that victory. This means that even if Democrats keep control of one or both chambers of Congress they went through the scare of feeling abandoned by the base and that alone is a learning moment for them and a teaching moment for Liberals. It should be completely clear now to every single democratic strategist and leader (including president Obama) that WITHOUT ITS LIBERAL BASE, THE DEMOCRATIC PARTY CANNOT WIN.
So, this is the moment for Liberals to make it very clear to Obama and the Democratic Party. In 2012 they can have either another 2008, another 2010 or even worse. They choice is theirs.