Probably because all the wealthy people who donated to the campaigns of the lawmakers are concerned about the expiration of the Bush Tax Cuts, which would send tax revenues skyrocketing.
However, the new administration promised in the "Pledge to America" that the tax cuts would be extended to all - not just the middle class.
The Democrats were in a standoff, as the tax cuts are not first and foremost on their agenda. They don't think that the wealthy should get tax cuts, and that the middle class shouldn't be burdened with extra expenses in the midst of the current economy.
The extensions that expire at the end of the month could be extended before the Senate and Congress leave their lame duck sessions, if the Democrats agree to pay for it with decreased government spending.
The unemployment extension fight is about to get more interesting.