Many voters are tired of the decisions that current leaders, in particular those in the Obama administration, are making. In particular, people grew angry over the passage of the controversial Healthcare legislation. Public options, loss of insurance coverage, limitations of insurance coverage, and forcing Americans to get coverage are all things that angered constituents.
The Bush Tax Cuts are set to expire, and the Democrats hope that this is their golden opportunity to turn voters away from the GOP. Many Republican leaders want to extend the tax cuts despite looming deficits and despite many provisions benefitting the wealthiest of Americans.
The Democrats are hoping to "make known" those who oppose simply passing middle class tax cuts without extending all of Bush's tax cut package. Sneaky move, but then again this is American politics.