Carolyn
As I recall, Bush said that the commission was not needed. He knew as well that it was a political ploy, but he also knew, imo, that to outright prohibit it would give the dims too much to squall about all the way to the election. By allowing it to proceed, hopefully it will be behind us before the election.
'Politically' the Bush administration had no choice but to go along and play this game, as bad as it was. They were in a 'no win' situation. Reticent about freely disclosing national security information involving the 9-11 incident, and appearing to be 'hiding something, they had no choice but to submit to the will of the Democrats on this political farce.