NEWARK, N.J. (AP) — A political mentor of Gov. Chris Christie who headed the agency that oversees New York City-area airports admitted Thursday that he used his position to get United Airlines to run direct flights to South Carolina so that he could easily visit his vacation home.

David Samson, the Republican governor's appointee to lead the Port Authority of New York and New Jersey, pleaded guilty to a bribery charge, acknowledging that he schemed with a lobbyist to delay approvals on a project as a way of pressuring the airline to re-launch the money-losing flight.

The ex-lobbyist, Jamie Fox, was charged with conspiracy to commit bribery, but his lawyer said he would fight the charges. Fox, a Democrat, went on to work for Christie as the state's transportation commissioner after ending his work for United.

Samson and Fox "both should have known better. They both did know better," U.S. Attorney Paul Fishman said. "It was an unacceptable abuse of public authority."

Fishman also announced that United would pay a $2.25 million fine for the role its officials played in the scheme.

United's then-CEO, Jeff Smisek, and two other executives left the airline last year after United conducted its own investigation. None of them has been charged with any criminal wrongdoing.

The company said in a statement that it accepted responsibility for certain conduct that led to the flight and agreed to "continue to enhance its compliance, anti-bribery and anti-corruption program policies and procedures."

A spokesman for Christie — Fishman's predecessor and the leader of presumptive Republican presidential nominee Donald Trump's transition team — didn't return a call or email seeking comment. The governor has now seen five close allies or high-level appointments either be indicted or plead guilty to federal charges.

Samson, who served as New Jersey's attorney general in 2002 and 2003, led the governor's transition team in 2009, and Christie appointed him to the Port Authority chairman's post in 2011.

Samson admitted that he conspired with Fox to pressure United to reinstate the "chairman's flight" to Columbia, South Carolina, not far from Samson's vacation home in Aiken, by removing from a board agenda discussion of a hangar that United wanted at Newark Liberty International Airport, Fishman said.

Around the same time, Chicago-based United was also pressing for concessions from the agency, including rent reductions and a commuter rail-line extension that would connect the airport directly to lower Manhattan.

"I hope they dance to my tune---let me know if there's a way to keep the pressure on this issue: it will save me a lot of heartache," Samson wrote in one email to Fox released by prosecutors.

United at first declined to renew the route because it was a money loser but then did because of the pressure, prosecutors said.

Samson took the flight, which left Thursday evening and returned Monday morning, 27 times between October 2011 and January 2014. United ended the flights three days after Samson resigned in March 2014 in the wake of the George Washington Bridge lane closure scandal that led to criminal charges against three other Christie allies.

Samson wasn't charged in the bridge investigation, in which the Christie allies were accused of closing lanes leading to the bridge to exact revenge against a politician. But an email from a Port Authority official to a Christie aide, both of whom were later charged, described Samson "helping to retaliate" after Port Authority executive director Patrick Foye ordered the lanes reopened.

The bridge investigation, combined with an earlier audit that called the Port Authority "challenged and dysfunctional," trained a spotlight on the powerful agency and eventually led to questions about Samson's interactions with United Airlines.

"It undermines the already eroded confidence the public has that government is being operated for their benefit," said New Jersey Assemblyman John Wisniewski, a Democrat who helped lead an investigative committee that investigated the bridge case. "The governor is either a bad judge of character when it comes to making high level appointments or is not as forthcoming as he'd like us to believe."

Prosecutors will recommend that Samson get a sentence of probation to 24 months behind bars under a plea agreement. Sentencing is scheduled for Oct. 20. Samson left the courthouse after posting $100,000 bond and surrendering his passport.

Fox's attorney Michael Critchley said his client would never jeopardize his reputation by engaging in illegal behavior and that the flight discussion was part of an arrangement that he thought was appropriate.

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Associated Press writer Maryclaire Dale, in Philadelphia, contributed to this story.