NEWARK, N.J. (AP) -- The government's key witness in the George Washington Bridge lane-closing scandal said people close to New Jersey Gov. Chris Christie gathered on a conference call to prep a cover story for the gridlock prosecutors contend was political revenge against a Democratic mayor.

NJ.com reported David Wildstein testified on Thursday that Phil Kwon, Christie's former pick for the state Supreme Court, and Regina Egea, who eventually served as the Republican governor's aide, helped prepare testimony that the closures were for a traffic study.

He said the pair prepped former Port Authority of New York and New Jersey executive Bill Baroni on what to tell lawmakers probing the incident.

Baroni is now on trial for federal crimes related to the September 2013 lane closures.

Defense attorneys countered that Wildstein's story had shifted from previous grand jury testimony.

Kwon's attorney, Geoffrey Berman said his client did not "perpetuate a cover story," and that he was never told the closures were to punish the mayor of Fort Lee.

A message left on social media with Egea was not immediately returned.

Information from: NJ.com