The most important man in the debt ceiling negotiations may not be President Obama, House Speaker John Boehner or ny other Member of Congress. It might well be Grover Norquist.

Norquist is the head of Americans for Tax Reform, a group that since the mid 1980s has been urging politicians to sign a pledge that they will not raise taxes or revenues during their time in office.

Hundreds of sitting House members — mostly but not all Republicans — have signed Norquist’s pledge. And that has proved to be a major stumbling block as negotiators try to find a solution to the debt ceiling standoff.

So, who is Norquist and how did he emerge as such a central player in this fight? Today’s “Fast Fix” episode explores that question. Don’t forget to check out all of our “Fast Fix” videos here. If you have a topic you want to see us break down in “Fast Fix” just email chris.cillizza@wpost.com with it.