A onetime top ally of the New Jersey governor, Chris Christie, said the governor and his New York counterpart, Andrew Cuomo, discussed releasing a false report to tamp down questions over the George Washington Bridge lane-closure scandal, the prosecution’s key witness testified on Tuesday.

David Wildstein, who pleaded guilty in the gridlock scheme and is cooperating with prosecutors, said the former Port Authority of New York and New Jersey chairman David Samson told him the governors discussed the idea in October 2013. The report would have attributed the lane closures to a traffic study, covering up the true reason for the closures: political retribution against the mayor of Fort Lee for failing to endorse Christie’s 2013 re-election, Wildstein testified.

The report was never issued.

Instead, Bill Baroni testified before lawmakers in November 2013, two months after the lane closures, that they were part of a traffic study.

Baroni, who served as Christie’s top appointed staff aide at the Port Authority, and Bridget Kelly, Christie’s former deputy chief of staff, are on trial facing wire fraud and civil rights charges. They have pleaded not guilty.

Wildstein said the idea for the report came as news reporters began to ask questions about the lane closures, which gridlocked the town of Fort Lee for four days.

“My understanding was that [Republican] Governor Christie and [Democratic] Governor Cuomo had discussed this,” Wildstein said under cross-examination on Tuesday, according to the Record, adding he was told the information by Samson. “My understanding at the time was that it would put an end to this issue.”

Cuomo spokesman John Kelly, who is not related to Bridget Kelly, denied the conversation between governors took place and criticized Wildstein as a “felon spinning a tale”.

“It’s just false and delusional,” Kelly said.

Messages left with Christie’s office were not immediately returned. A message left with Samson’s attorney has not been returned. Samson pleaded guilty in another case to using his role as Port Authority chairman to influence United Airlines to reinstate a money-losing route closer to his vacation home and is awaiting sentencing.

Wildstein, a former executive at the Port Authority of New York and New Jersey, which oversees New York-area bridges and tunnels, testified earlier that Baroni told Christie about the traffic jams as they were happening and said the Democratic mayor of Fort Lee was not happy that he was not getting his calls returned.

Christie has not been charged and says he did not authorize the closures or play a role in covering them up.