The bureaucracy has way more control over funding flows than the chief executive.The reason for thinking that anti-AGW research will have got enough funding is that the US government under Bush was for many years adamantly opposed to any action to control GW - and stated that there was no evidence for it. That stance may have changed (why?) but during those years they would have been looking hard for any evidence against AGW.
Had Bush been able to set up an anti-AGW bureau and staffed it with people he or some one sympathetic to his position had vetted I might agree. However, as far as I know that was not the case.
For good or ill the chief executive in our system just doesn't have much power.
BTW I was reading a biography of A.T. Mahan and his troubles with the US Navy re: the Naval War College. Twas ever thus. If the guys running the organization are against your policy they can stall you almost as long as they want. Even if the executive is in your favor. And even back then (1890) firing people to put the fear of God in them was difficult.