Chris Christie has said he was "embarrassed and humiliated" by the political revenge scandal engulfing his presidential hopes, as it emerged a woman died after ambulances were delayed by traffic jams orchestrated by his office.
Yet the early front-runner for the 2016 Republican nomination denied being personally involved, fired a "deceitful" senior aide, and heaped blame on his staff, whose behaviour he called "completely unacceptable".
"I've come out here today to apologise to the people of New Jersey," Mr Christie told a press conference. Members of his team "showed a lack of respect for the appropriate role of government and for the people they were trusted to serve," he said.
Private emails published showed that the fired aide, Bridget Kelly, ordered needless road closures that caused days of jams last September in Fort Lee, whose mayor Mark Sokolich had refused to endorse Mr Christie's re-election as New Jersey governor.
They sharply contradicted Mr Christie's angry denials last month that his team were behind the closures, which were eventually explained as a "traffic safety study".
Mr Christie said yesterday Ms Kelly had promised him this was true. "I've terminated her employment because she lied to me," he said, claiming to be "heartbroken" by her betrayal.
"I had no knowledge or involvement in this issue, in its planning or its execution," said Mr Christie. "And I am stunned by the abject stupidity that was shown here."
His remarks came after it emerged that medics rushing to an unconscious elderly woman in Fort Lee were stuck in a jam caused by the closures of lanes to the George Washington bridge, which connects New Jersey with New York. The woman later died of a cardiac arrest at a hospital.
At least three other ambulances were delayed by the closures. Police have also complained that their search for a missing four-year-old child was hindered. The child was eventually found.
Paul Fishman, the state's most senior federal prosecutor, said yesterday that his office was investigating whether laws had been broken. Aside from more serious potential charges, the use of government resources for political purposes is illegal.
The emails showed Christie aides mocking Mr Sokolich's frantic calls about the jams and dismissing school pupils stuck in gridlocked buses as "children of Buono voters". Mr Christie went on to beat Barbara Buono, his Democratic opponent, comfortably in November's election.
After a day spent preparing his response, he insisted yesterday that he had "no inkling" of his staff's involvement in the closures until the emails were published on Wednesday morning. "This is not the tone that I've set over the last four years in this building," he said.
Yet he was forced to insist "I am not a bully," as the crisis threatened his carefully-crafted image as a viable US president who forges bipartisan relationships to solve problems while unprecedented political division paralyses Washington.
Other senior advisers were copied into the emails at some points, prompting allegations that they reflected widespread practice.
"It's going to be very difficult to convince the public he was out of touch with what was going on," said Bob Ingle, Mr Christie's biographer. "And if he were, is he going to look like the in-charge guy that people are after?"
Ms Kelly's emailed order for "some traffic problems in Fort Lee" was executed by David Wildstein, a schoolmate of Mr Christie. Mr Wildstein resigned last month. (© Daily Telegraph, London)