Truth be told, what the Democrats are doing today is smart short term politics.
The scenario will probably play out like this:
A) Piss off your base by refusing to Impeach / Defund
B) Strengthen your gains with the squishy middle, do not risk pissing them off
C) Count on the base having nowhere to go come election time
D) Win in 2008 and MoveOn from there
Essentially, they are following a smart political strategy.
But in the mean time…