New Jersey Gov. Chris Christie is ratcheting up his response to revelations that his aides shut down the world’s busiest bridge to punish a political foe, hoping to limit any additional political damage to his administration and his 2016 presidential ambitions.

Christie in his annual State of the State address admitted that “mistakes were clearly made” and vowed to cooperate with all “appropriate inquiries” into the incident. He later announced that he appointed a legal team to work with state and federal investigators and to conduct an independent internal investigation.

Christie insists he didn’t know his close aides had plotted last year to shut down access lanes to the George Washington Bridge to create a massive traffic jam that paralyzed neighboring Fort Lee, N.J., whose Democratic mayor refused to endorse Christie’s re-election.

“This administration is committed to ensuring that what happened here never happens again,” Christie said. “That’s what the people of New Jersey deserve.”

A Democratically led legislative committee and a federal prosecutor are investigating. Democrats charge that others in Christie’s administration — and possibly Christie himself — knew about the lane-closing plot that Christie at first denied ever happened.

Christie’s political standing took a predictable hit among the already skeptical Tea Party wing of the GOP because of the budding scandal. But Republican political operatives warned that Christie could also lose the support of Establishment Republicans who were most enthusiastic about him running for president if there are any additional revelations of wrongdoing.

Christie generally got high marks for his initial handling of the controversy, including his repeated apologies and the firing of two of the aides involved. And there was no immediate indication that his problems dampened his plans to travel the country as chairman of the Republican Governors Association to raise money for GOP candidates and to network with the operatives and party donors he will need for a presidential run.

“As of now, it doesn’t have much of an impact on him,” said Fred Malek, the finance chairman of the governors association and a major GOP power player. “He’s emerged as a strong and forthright leader who handles adversity well.”

Former New York City Mayor Rudy Giuliani, a one-time Republican presidential contender, and Wisconsin Gov. Scott Walker, who also may run for president in 2016, were among those who stood by Christie.

“He said he didn’t know,” Giuliani said. “I think it’s pretty darn credible. He wouldn’t make this blanket denial unless it’s not true.”

Walker called Christie shortly after news of the scandal broke and said he was satisfied with Christie’s handling of the situation so far.

“He told me exactly what he said to the public and I have every reason to believe him,” Walker said, “and going forward I think he handled it the way we’d expect a leader to handle it.”

Christie has worked tirelessly to foster his brand as a straight-talking, no-nonsense chief executive who puts his constituents ahead of political gain — exemplified by his handling of the devastation to his state by Hurricane Sandy. If the scandal did any lasting damage to that Image, Christie could benefit from the fact that the presidential race is two years away, time enough for the controversy to fade.

“I’m pretty sure that this is going to go away,” Giuliani said. “Obviously, it can take a while. There are going to be more iniquities … but I don’t think it’s going to be fatal.”