Embattled New Jersey governor Chris Christie has fired one of his top aides, who allegedly engineered traffic jams on a New York bridge to punish a political opponent.
Mr Christie is a rising star in the Republican Party and was tipped to run for President in 2016, but has struggled to distance himself from the scandal.
“I am who I am but I am not a bully,” he said in a news conference on Thursday.
Despite initially denying anyone in his office was involved, he has dismissed his deputy chief of staff, Bridget Anne Kelly, “ because she lied”, he said.
Emails leaked earlier this week implicated her in the closure of lanes on the George Washington Bridge between Fort Lee and New York, which caused havoc over four days in September.
One of the busiest bridges in the world was gridlocked, stopping paramedics getting to emergencies, including a call about an unconscious 91-year-old woman who later died in hospital.
Officials claimed the Port Authority was “reviewing traffic safety patterns” but the messages appear to show the closures were to punish Fort Lee Mayor Mark Sokolich for not endorsing Mr Christie for re-election.
“Time for some traffic problems in Fort Lee,” Ms Kelly wrote in August in to David Wildstein, a top official on the Port Authority of New York and New Jersey.
“Got it,” he replied.
Two days before the closure, he wrote: “I will call you Monday AM to let you know how Fort Lee goes.”
Mr Christie called the emails “unacceptable” in a statement after they were made public.
He told a press conference: “I am embarrassed and humiliated by the conduct of some of the people on my team.”
Two more of his staff, including Mr Wildstein, have already resigned.
Mr Wildstein was found in contempt by a legislative committee on Thursday for invoking his right against self-incrimination and refused to answer questions.
The scandal has already been dubbed “bridge-gate” and sparked comparisons to Nixon.
Mr Christie has travelled to Fort Lee to personally apologise to Mr Sokolich, the alleged target of the scheme who was called a “ little Serbian” in the emails.
The Fort Lee mayor had called the revelations “appalling” and demanded for anyone responsible to resign.
”When it's man-made and when it was done with venom and when it was done intentionally, it is, in my mind, the prime example of political pettiness," he said.
The chief federal prosecutor in New Jersey, attorney Paul Fishman, said he is ”reviewing the matter to determine whether a federal law was implicated".
Using public resources for political ends can be a crime.
Additional reporting by Associated Press