Congressional Budget Office sticks its neck out

CBO just released a damning forecast on Obamacare.  They predict 800,000 lost jobs, 2.5 million workers put on part time, and a drag on the economy equivalent to a 1% tax hike.  Ouch. 
I wonder where CBO found enough backbone to speak up.  When they were forcing Obamacare down our throats, CBO released several studies claiming that it wouldn't be all that bad.  While anyone of common sense knew Obamacare would be expensive as a medium sized war.  At the time, excuses were made for CBO, claiming that they were required to forecast based upon the presumptions passed to them by Congress rather than sure knowledge of what will really happen.  For instance Congress could ask for a forecast with the assumption that the federal deficit would shrink.  Everyone knows that is unlikely to happen.  But if it did, wonderful things might happen, and CBO would dutifully forecast wonderful things.
   Yesterday's forecast was a bummer for Obama.  The TV news reported a lot of huffing and puffing from the White House. 
   Is this a sign that Obama is a lame duck?  And CBO figures he will be ineffectual if he retaliates against them?