From the guardian:
[Grover] Norquist holds no elected office but is one of the most powerful figures in Washington, head of a lobbying and activist group Americans for Tax Reform. Democrats blame him for the impasse over deficit reduction.
The Democratic senator and former presidential candidate John Kerry described him as the “13th member” of the 12-member congressional super-committee given the task of drawing up a plan to reduce the country’s $15tn national deficit.
Kerry and other Democrats complained that Norquist’s name was repeatedly invoked by the Republicans, and the word “pledge” came up over and over again.