The leader of the Transportation Security Administration, which was established last winter to protect travelers after September 11, was forced out of his job today as questions intensified about whether the agency had moved quickly enough to improve airport security.

The surprise firing of John Magaw, who was under secretary of transportation for security, is the latest indication that his agency has not made enough progress in the huge job of tightening security at the nation's 429 commercial airports.

The dismissal underscores the administration's struggle to achieve its domestic security goals.

"He was eased out. There was a lot of back-room talk about his management style, or lack thereof, ... tending to gold-plate everything."