Bush signed a Presidential Executive Order prior to this though that declared in the interest of national security the President has the authority to deputize federal officials with the power to declassify classified information when necessary to keep the public informed through the media.
Gotta love this admin. They think of everything. Normally only the President has the authority to declassify something on the fly, bypassing the normal procedures, but this PEO allowed Bush to grant authority to do this to Cheney, Card, and others.