This story has been updated.

New Jersey Gov. Chris Christie (R) announced Friday that David Samson, chairman of the Port Authority of New York and New Jersey, had resigned earlier in the day. The resignation will be effective immediately.

"He believes that the best way to start a new year at the Port Authority is with new leadership," Christie said. "In line with that belief, David tendered his resignation to me this afternoon, effective immediately."

Christie stressed 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 does not believe that Samson played a crucial role in the George Washington Bridge scandal, which has engulfed Christie's year so far.

“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."

Samson, a former state attorney general, released a statement on the resignation soon after Christie mentioned it in the news conference Friday afternoon, stating, “Over the past months, I have shared with the Governor my desire to conclude my service to the PANYNJ. The timing is now right, and I am confident that the Governor will put new leadership in place to address the many challenges ahead.”

An internal investigation released by Christie's office Thursday, which provided behind-the-scene details of the so-called Bridgegate scandal and was greeted skeptically by critics, called for the Port Authority to be restructured. Samson was not interviewed by the law firm conducting the investigation. Page 140 of the report states that his law firm Wolff & Samson “declined our request for interviews and documents."

Samson and his firm are also being investigated by federal prosecutors for potential conflicts of interest with the Port Authority. A grand jury subpoena was issued in early March for information regarding two bridge contracts awarded by the Port Authority to clients of Wolff & Samson.

In the internal investigation, the Port Authority's e-mail chains about who leaked the bridge story to the Wall Street Journal feature Samson prominently. He told Scott Rechler, who is on the Port Authority's board of commissioners, "I just read it and it confirms evidence of [authority executive director Patrick Foye] being the leak, stirring up trouble -- this is yet another example of a story, we've seen it before, where he distances himself from an issue in the press and rides in on a white horse to save the day. ... [In] this case, he's playing in traffic, made a big mistake." Rechler did not agree with Samson that Foye was the leak.

Christie said that he asked Samson in January if he had any knowledge of what was going on, following news reports on the apparently politically motivated scheme to create traffic jams by closing lanes leading to the George Washington Bridge. The internal report released Thursday found that the plan was hatched by David Wildstein, a Christie associate who worked for the Port Authority.

According to Christie, Samson said, "Absolutely not." The governor said Friday that "it rang true at the time."

On Sept. 13, Wildstein, appointed to the Port Authority by the governor, sent an e-mail to Christie aide Bridget Kelly saying that Samson would help them "retaliate" after lanes on the George Washington Bridge were re-opened.

Christie told reporters Friday that Samson had "no idea" what Wildstein was talking about. Both Wildstein and Kelly were fired after news of the scandal broke, and the internal investigation also blames them for the incident.

"I obviously believe that having David Wildstein at Port Authority was a mistake," Christie said Friday.

Christie said he got Samson's resignation call just two hours before the news conference, and that picking a new Port Authority chair and getting a nominee approved will take some time.

“I suspect the Senate hearing for the forthcoming nominee to replace Samson will need to be held at Giants Stadium," Heath Brown, a professor of political science at Seton Hall University, wrote in an email. "The scrutiny of that nominee will be unprecedented in NJ history."

As for the future of the Port Authority, Christie says he hasn't talked to New York Gov. Andrew Cuomo (D) about it yet, although he sees "some merit" in splitting the agency into two departments run individually by the two states.

The first question asked at the press conference was related to the 2016 presidential race, which many think will involve the New Jersey governor. Christie said if he were to run -- and he made sure to stress the hypothetical nature of his answer -- the bridge scandal would not play a large role in his decision. "That's simply not a way I'm going to make a decision," he said.

Correction: A previous version of this story said Professor Heath Brown was from Seton Hill University. It is Seton Hall University.