WASHINGTON — It began with a familiar pledge: President Trump’s audience, he promised, was going to be very proud of him.

“Hi, Drumstick,” Mr. Trump called out on Tuesday, preparing to exercise his least controversial executive authority. “Oh, Drumstick, I think, is going to be very happy.”

It ended with characteristic introspection.

“I feel so good about myself,” the president said softly, appraising his own clemency, laying a hand on the bird after seeking permission to touch it from turkey professionals.

Mr. Trump looked upon the crowd in the Rose Garden and announced his decision: The animal was hereby pardoned for the crime of being born a turkey.