What Should Progressives Do to Hold President Obama Accountable?

As far as I am concerned, voting Republican is not an option. That party is opposed to everything that I stand for. Sitting out the 2012 Presidential Election is not an option. If progressives and Democrats decide not to vote, that will only help the Republican Party win the Presidency.

Unfortunately, our options are limited. There is no viable progressive alternative to President Barack Obama. How do we hold the President accountable without empowering the opposition?