New Jersey Gov. Chris Christie holds a news conference on March 28, 2014, at New Jersey State House in Trenton.

Christie Adviser Says the Governor Knew

Bill Stepien, Chris Christie's former political tactician, breaks with his former boss on Bridgegate.

New Jersey Gov. Chris Christie holds a news conference on March 28, 2014, at New Jersey State House in Trenton.

New Jersey Gov. Chris Christie has maintained he was not aware of any plans to close lanes on the George Washington Bridge. 

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Gov. Chris Christie's former campaign manager says the New Jersey governor knew about a plan to close lanes on the George Washington Bridge the day before he held a news conference pronouncing he didn't.

The potentially explosive assertion is included in a letter from former Christie adviser Bill Stepien's attorney that demands changes to a governor's office report asserting that Stepien had misled Christie on the incident.

From The Bergen Record:

Bill Stepien contends that he told the governor on Dec. 12, a day before Christie made his public comments, that he had been approached by Port Authority executive David Wildstein with the idea of closing the lanes, Stepien’s attorney wrote in a letter released Wednesday.

“There is no dispute that at that December 12, 2013, meeting, Mr. Stepien informed the governor that the proposed ‘lane realignment’ was one of Mr. Wildstein’s ‘50 crazy ideas,’ the attorney, Kevin H. Marino, wrote in a letter that demanded changes to a|report commissioned by Christie that found that Stepien had misled the governor.

[READ: Chris Christie Remains Afloat]

Stepien's attorney says Christie "misspoke," wording that potentially provides the governor some wiggle room in explaining the discrepancy. The former ally does not accuse Christie of an outright lie or that he was at all involved in orchestrating the original scheme.

But this development still marks the first public defection of a top Christie confidante regarding the storyline the governor has laid out about "Bridgegate" controversy that has embroiled his administration and jeopardized his plan to seek the presidency in 2016.

At the Dec. 13 news conference, Christie told reporters that he had "made it very clear to everybody on my senior staff that if anyone had any knowledge about this that they needed to come forward to me and tell me about it and they’ve all assured me that they don’t.”

Stepien says that, in fact, he did, the day before.

In Christie's political orbit, there weren't many people closer to him than Bill Stepien.

He managed both of Christie's gubernatorial bids and was set to join Christie as a strategist at the Republican Governors Association before Christie canned him.

"I was disturbed by the tone and behavior and attitude of callous indifference that was displayed in the emails by my former campaign manager, Bill Stepien," Christie said in his January news conference acknowledging his administration's role in "Bridgegate" and announcing the firing of aides he deemed responsible.

Just as "Bridgegate" was losing some of its steam in the media and beginning to fall out of national headlines, Stepien has re-emerged to reignite a debate about Christie's veracity.

As recently as Wednesday, Christie was poo-pooing the impact of the bridge flap during a conversation in Washington with CBS News’s Bob Schieffer.

[OPINION: Chris Christie Returns to Form at CPAC 2014]

"I think it will have none because I didn't do anything," Christie said, when asked to assess the impact "Bridgegate" would have on his political future. "A couple of staff people do something that they shouldn't have done, I fire them, and all of a sudden this becomes the biggest story in the country for a couple of months," he said, "because I guess you guys weren't doing anything else down here."

Stepien's willingness to step out and directly challenge Christie is a troubling development for the governor. There's no telling how hard he'll fight to clear his own reputation and there's only a few people who know more about the governor's political past.