In December 2013, as the "Bridgegate" scandal was unraveling, New Jersey Governor Chris Christie's chief spokesman learned the truth: that lanes had been closed at the George Washington Bridge to punish a local mayor for political reasons.

That was the testimony from former Port Authority of New York and New Jersey executive David Wildstein on Wednesday, who told jurors in Newark federal court he informed Christie's press secretary Michael Drewniak that he executed the scheme with the approval of Christie aides.

Wildstein has said several key figures in Christie's inner circle knew about the plot as it was occurring or soon afterward - including Christie himself, who was told of the closures by Wildstein as they unfolded in September 2013, according to Wildstein's testimony on Tuesday.

Christie, who is not accused of wrongdoing, has repeatedly denied any knowledge of the plot at the time, but Wildstein's testimony has bolstered the government's assertion the governor knew about the scandal earlier than he has acknowledged.

The scandal helped derail Christie's bid for the 2016 Republican presidential nomination and could endanger his best chance at a political future: a role in Donald Trump's administration should the Republican presidential candidate win a Nov. 8 election.

The governor's former deputy chief of staff, Bridget Kelly, and a former Port Authority executive, Bill Baroni, are charged with deliberately creating gridlock in Fort Lee, New Jersey, after the town's mayor declined to endorse Christie's 2013 re-election bid.

Wildstein said on Wednesday he met with Drewniak on Dec. 4 and offered to resign.

"I told him the stories were out of control," Wildstein said. "This wasn't going away."

Drewniak has previously confirmed that Wildstein told him of the closures, but has denied knowing it was political payback.

Wildstein also said he met with Christie's chief counsel, Charlie McKenna, two days later and told him about the scheme, though he did not say whether he disclosed the motivation for the plot.

Wildstein previously said he informed Michael DuHaime, a Christie adviser, in November. He has also testified that Christie's campaign manager, Bill Stepien; David Samson, the chairman of the Port Authority; and a board member, Pat Schuber, were aware of the plot beforehand.

Stepien's lawyer has said he had no role in the scheme, while Samson and Schuber have denied advance knowledge.

Defense lawyers began questioning Wildstein on Wednesday and sought to portray him as the true mastermind of the scheme, even though Baroni was nominally his superior.

Michael Baldassare, a lawyer for Baroni, also suggested Wildstein's testimony was biased because he is seeking a reduced sentence after pleading guilty to two counts of conspiracy.