New Jersey Gov. Chris Christie on Friday announced the resignation of David Samson, chairman of the Port Authority of New York and New Jersey, the agency at the heart of the scandal that has engulfed Christie’s administration this year and complicated his presidential aspirations.

Christie (R) made the announcement during his first news conference since January, part of an orchestrated effort over two days to try to put the bridge-closing scandal behind him. Christie also gave two television interviews Thursday and Friday and released the results of an internal investigation that essentially exonerated him in the controversial closing of several traffic lanes on the George Washington bridge in September.

Of Samson’s resignation, Christie said, “He believes that the best way to start a new year at the Port Authority is with new leadership.”

Christie said during the news conference, with a raised voice, that he did not ask Samson to resign, saying that the chairman had raised the idea of leaving about a year ago and Christie had asked him to stay. He said he does not believe that Samson played a crucial role in the scandal.

“I think that his role was not central in any of these things, nor has it ever been alleged that his role was central,” he said. “He is 74 years old, and he is tired.”

“Over the past months, I have shared with the Governor my desire to conclude my service to the PANYNJ,” Samson said in a statement. “The timing is now right, and I am confident that the Governor will put new leadership in place to address the many challenges ahead.”

Greeted skeptically by critics, the internal investigation called for the Port Authority, which operates the bridge, to be restructured.