NEWARK, N.J. -- Gov. Chris Christie was told about the epic 2013 traffic jam at the George Washington Bridge while it was underway, seemed happy about it and joked sarcastically that there was nothing political going on, a former loyalist testified Tuesday in the scandal that helped destroy Christie’s White House ambitions.

David Wildstein, a former executive at the agency that oversees New York-area bridges and tunnels, took the stand for the prosecution at the trial of two one-time Christie allies accused of engineering the four days of gridlock to punish a Democratic mayor for not endorsing Christie. Wildstein has pleaded guilty.

Wildstein’s account was the first testimony to suggest Christie knew about the scheme as it was unfolding.

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Christie has repeatedly denied that and has not been charged with a crime.

On Tuesday, the Republican governor said: “All kinds of stuff is going on up in a courtroom in Newark. I want to be really clear: I have not and will not say anything different than I’ve been saying since January 2014. No matter what is said up there, I had no knowledge prior to or during these lane realignments.”

Bridget Kelly, Christie’s former deputy chief of staff, and Bill Baroni, a former executive at the Port Authority of New York and New Jersey, are on trial, charged with conspiracy, fraud and civil rights deprivation in the alleged political revenge plot.

Wildstein, a former high-ranking official at the Port Authority, testified that he was present when Christie was told about the traffic in Fort Lee on the third day of the gridlock during a Sept. 11 memorial event in New York.

Wildstein said Baroni told Christie there was “a tremendous amount of traffic in Fort Lee” that morning and that Mayor Mark Sokolich was “very frustrated” he wasn’t getting his phone calls returned. Baroni then told the governor that Wildstein was watching over the situation, Wildstein testified.

“Well, I’m sure Mr. Edge would never be involved in anything political,” Christie responded sarcastically, and then laughed, according to Wildstein. “Wally Edge” was a pseudonym Wildstein used while running a New Jersey politics website.

Prosecutors showed the jury several photographs of Baroni, Wildstein and Christie talking that day.

Federal prosecutor Lee Cortes asked Wildstein if he and Baroni were bragging about the traffic jams.

“Yes, very much so. This was our one constituent,” Wildstein replied, referring to Christie. “I was pleasing my one constituent. I was happy that he was happy.”

Christie’s name is on a list of potential witnesses at the trial.

The closing of two of three access lanes to the George Washington Bridge caused bumper-to-bumper traffic in Fort Lee, held up school buses and emergency vehicles, and left drivers fuming for hours at one of the busiest spans in the world. The bridge connects New Jersey to New York City.

David Wildstein testifies in Bridgegate trial in Newark, N.J., on Monday, Sept. 26, 2016. Jane Rosenberg

For months afterward, Port Authority officials insisted the lane closings were part of a traffic study. But the scandal broke wide open with the release of emails and text messages, including one from Kelly to Wildstein in which she said: “Time for some traffic problems in Fort Lee.”

At the time of the traffic jams, Christie was running for re-election, and his campaign was trying to secure endorsements from local Democratic officials like Sokolich in order to win a big landslide victory and demonstrate the governor’s broad appeal as a potential candidate for president.

In the end, the scandal helped sink Christie’s White House campaign. Christie once topped the national polls ahead of the 2016 GOP primaries but dropped out after New Hampshire and said recently that the scandal probably influenced Donald Trump’s decision not to pick him as his running mate.

Trump said last December that Christie “totally knew” about the lane closings. The GOP presidential candidate has since tapped Christie to lead his transition team.

The scandal has brought to light some of the hardball tactics used by the Christie administration and reinforced his reputation as a bully.

Last week, Wildstein testified Christie’s office used the rich and powerful Port Authority to reward local officials whose endorsements were sought during the 2013 re-election campaign.