Technically he never had a supermajority of Democrats in the Senate. It was only with caucusing with independents that they could break the 60 vote threshold to end filibusters.
They had a caucused supermajority in the Senate from:
July 8th, 2009 - August 25, 2009
and
September 25, 2009 - February 4, 2010
Or about 4 months to make any change he wanted (that the caucus which included Joe Lieberman, an extreme defense hawk, and Arlen Spector who just switched parties, approved).
They had a caucused supermajority in the Senate from:
July 8th, 2009 - August 25, 2009 and September 25, 2009 - February 4, 2010
Or about 4 months to make any change he wanted (that the caucus which included Joe Lieberman, an extreme defense hawk, and Arlen Spector who just switched parties, approved).