The former chairman of the agency that controls New York City-area airports conspired with a United Airlines lobbyist to use his post to get the airline to run direct flights to South Carolina so that he could more easily visit his vacation home, officials said Thursday.

David Samson, a political mentor to Republican Gov. Chris Christie, pleaded guilty to a corruption charge that he wrongfully used his Port Authority of New York and New Jersey post. The ex-lobbyist, Jamie Fox, was then charged with conspiracy to commit bribery, U.S. Attorney Paul Fishman said.

United didn't immediately respond to a request for comment on Thursday's news, but Fishman announced that the company would pay a $2.25 million fine for the role its officials played in the scheme.

Former United CEO Jeff Smisek and two government relations executives left the airline last year after United conducted its own investigation. None of them has been charged with any criminal wrongdoing.

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

Prosecutors will recommend that Samson get a sentence of probation to 24 months behind bars under an agreement.

Sentencing is scheduled for Oct. 20. His attorney, Michael Chertoff, said he wouldn't have any comment until then. Samson left the courthouse after posting $100,000 bond and surrendering his passport.

After leaving his job with United, Fox was appointed the state's transportation commissioner by Christie. Fox, a Democrat, stepped down in October 2015. His attorney wasn't immediately available to comment.

United ended the half-filled flights three days after Samson resigned his Port Authority post 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 Christie allies were accused of causing traffic problems 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.

Samson, a former state attorney general, led the governor's transition team in 2009, and Christie appointed him to the Port Authority chairman's post in 2011.

He resigned from the Port Authority a day after a law firm's taxpayer-funded report cleared Christie of wrongdoing and laid much of the blame for the lane closures on the Christie aide. Samson wasn't interviewed for the report.

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.

When Samson was chairman, United resumed direct flights to the South Carolina airport. Around the same time, Chicago-based United was pressing for concessions from the agency, including the new hangar at Newark, rent reductions and a commuter rail-line extension that would connect the airport directly to lower Manhattan.

The Port Authority also wanted to increase flights to Atlantic City, while New Jersey struggled to revitalize the seaside gambling resort. United began those flights between Houston and Chicago in April 2014, but they were typically half full and United canceled the service that December.