The intensifying investigation, which threatens to undermine Christie's second term and his chances at a 2016 presidential run, revealed last week that high-ranking Christie aides and appointees were involved in ordering lane closings in September as apparent political payback that led to massive gridlock in the town of Fort Lee.
A new special Assembly committee, given subpoena power and a special counsel, will be charged with finding out how high the plot went up Christie's chain of command, said a leading state Democrat, Assembly Majority Leader Lou Greenwald.
"It is clearly an abuse of power," he said. "The question is, who abused their power and how high did it go?"
The committee will focus exclusively on the traffic jams in Fort Lee, whose mayor has said he believes the lanes were closed to punish him for not endorsing Christie. The panel will be chaired the head of the Assembly transportation committee who launched the initial investigation into the lane closings, John Wisniewski.
The state Senate announced that it planned to establish its own committee, also with subpoena power.
Christie has apologized over the lane closings but denied involvement. He also fired a top aide and cut ties with a political adviser who'd been widely seen as a potential campaign manager if Christie runs for president. Wisniewski said Monday that both of them could receive subpoenas soon, though he could subpoena their emails first.
Wisniewski also referred contempt charges against another Christie loyalist, David Wildstein, to a county prosecutor. A former Christie appointee to a powerful New York City-area transit agency, Wildstein was subpoenaed to testify before lawmakers but invoked his right against self-incrimination and refused to answer questions or even confirm that he worked for the agency.
Wildstein's lawyer indicated that an appeal would be filed, according to prosecutor Joseph Bocchini. The lawyer didn't return messages seeking comment.
The scandal widened last week when documents were released showing that, in addition to the apparent political retribution by Christie's team, the mayor of Fort Lee asked Christie's top deputy at the transit agency whether the lane closings were a punishment for him and why.
The mayor, Democrat Mark Sokolich, had noted that he didn't endorse Christie for re-election but told CNN last week that he couldn't recall "a specific request to endorse" from the governor's campaign staff, though other events could be seen as an attempt to attract his endorsement.
Sokolich shifted away from that assertion Monday, saying in an interview at his law office that he did consider a request from the Christie campaign but ended up supporting the Democratic candidate. He declined to say why he changed his account or answer other questions about his interaction with the campaign.
The scandal has changed the tone of state politics.
Christie must figure out how to address it when he gives his State of the State address on Tuesday. His administration has not revealed what he might say, but certainly it will now have a bigger audience and announcements about tax cut plans will no longer be the most anticipated part. The same could be true at the governor's inauguration for a second term next week, set to take place on Ellis Island, historically a gateway to the United States for millions of immigrants. The setting is meant to showcase Christie's inclusiveness and ability to appeal to a broad swath of voters.
He also faces renewed interest in the state's use of $25 million in federal money for an ad campaign to promote New Jersey tourism after Superstorm Sandy. U.S. Rep. Frank Pallone, a New Jersey Democrat, announced Monday that the inspector general at the U.S. Department of Housing and Urban Development will audit the campaign.
Christie and his family appeared in the ads. His administration chose a politically connected public relations company over another firm that had bid $2 million less. The winning bidder proposed using Christie in the ads, while the other did not.
Revelations about the contract caused a bit of a flap in New Jersey last year as Christie was seeking re-election.
Colin Reed, a spokesman for Christie, derided the timing of Pallone's announcement and noted that the ad campaign was part of a plan approved by the federal government.
"Federal agency reviews are routine and standard operating procedure with all federally allocated resources to ensure that funds are distributed fairly," Reed said in a statement. "We're confident that any review will show that the ads were a key part in helping New Jersey get back on its feet after being struck by the worst storm in state history."
Reed also noted that HUD Secretary Shaun Donovan praised the use of some money to promote a return to the state's beaches, a major tourist attraction and economic driver for New Jersey.
Ian O'Connor, a spokesman for the inspector general's office, said the audit is being done at the request of Congress. He would not comment further. Pallone had requested an investigation in August.
Associated Press writer Katie Zezima contributed from Fort Lee.