Via Road to Surfdom, by way of Atrios:

SECRETARY POWELL: Well, one, we didn't put together just the coalition of the willing. A coalition is always a coalition of the willing. And this particular coalition of the willing now has 47 nations; 47 nations are openly members of the coalition, and have asked to be identified with this effort. And there are many other nations that for a variety of reasons don't want to be publicly identified, but are also a part of the coalition of the willing.

That quote comes from March 26, 2003.