Trenton, N.J. - Embattled New Jersey Gov. Chris Christie struggled Tuesday to regain his footing, giving an address in which he called upon the state to refocus on his agenda. But his inability to explain the actions of top aides and allies in causing a massive traffic jam has spawned a storm of conjecture about what their real motives may have been.

The explanation - that it was a move to punish a Democratic mayor who had refused to endorse the re-election bid of Christie, a Republican - is being met with skepticism, both in the halls of the State House in Trenton and in Fort Lee, where the tie-up occurred for several days in September.

On Thursday, two special legislative committees will begin investigating the episode. The panels will have subpoena power, which means in the coming weeks and months, a parade of former and current Christie administration officials - as well as many of the governor's closest political associates - will be called to testify.

In his annual State of the State address, the governor touched upon the controversy only briefly, employing a phrase that has become classic among politicians who are trying to distance themselves from trouble in their own ranks. "Mistakes were clearly made," he said.

"I know our citizens deserve better," he added. "I also want to assure the people of New Jersey today that what has occurred does not define us or our state."

Christie pledged to "cooperate with all appropriate inquiries" regarding the closure of two access lanes to the George Washington Bridge. Recently revealed emails suggest it was done for political purposes.

In Trenton, however, there remain more questions than answers as to why Christie's allies did what they did.

"The missing link for me has always been: Why would you do such a thing?" said Loretta Weinberg, a Democrat who is the state Senate majority leader and a frequent Christie antagonist representing Fort Lee.

"Because nobody has come forth with the answer, everybody is left to speculate. I can't give a logical explanation," she said. "I've heard so many different theories that I can't really offer more than conjecture."

"We all talk to each other with, 'Do you think . . .,' " Weinberg added.

The most popular theory is that Christie's strategists were trying to punish Mark Sokolich, Fort Lee's Democratic part-time mayor, because he had not endorsed the governor.

Sokolich declined a request for an interview, but one longtime member of the borough's all-Democratic council said that explanation makes no sense.

Councilman Joseph Cervieri Jr. said the mayor discussed the possibility of endorsing Christie late last spring or in the early summer and quickly dismissed it.

"The whole conversation was maybe a two-minute conversation," Cervieri said. That such a minor slight could trigger such a major retaliation months later, as the governor was heading for a landslide victory, is "a possibility - but what is the probability?"

Nor would that be in keeping with the kind of immediate, targeted retribution exacted of another Democratic mayor, Steven Fulop of Jersey City, who said his relations with the Christie administration were abruptly cut off after he declined to endorse the governor in July. That same day, Christie's aides canceled meetings with administration officials regarding recovery efforts from Hurricane Sandy.

Cervieri has his own theory, gleaned largely from speculation that he has heard in the news media: Perhaps Weinberg, who had tangled with Christie over judicial nominations, was the target.

Still other conjecture swirls around a billion-dollar redevelopment project that is underway at the foot of the George Washington Bridge.

"Part of the marketing is easy access to the George Washington Bridge," Weinberg said.

State legislators from both parties on Tuesday said Christie's troubles will not necessarily damage his standing with the Democratic-controlled legislature, which has worked unusually closely with the governor since he assumed office in January 2010.

Several Democrats said Christie's friendly relationship with state Senate President Stephen Sweeney, a Democrat, will continue to reap dividends for the governor as he pursues his agenda, which includes education reform, property tax cuts and revamping the state's pension system.

Sweeney, speaking in the state Senate earlier Tuesday to open up a new session, did not blast Christie or his administration but offered a suggestion to his colleagues, saying, "The headlines and the recent press cannot become a distraction."

"It's a natural marriage," Democratic state Sen. Joe Vitale said of the Christie-Sweeney alliance. "It's kind of like the nuclear option. They know they can blow each other up, but they don't want to do that. I don't see the bridge issue affecting that bond. That bond goes beyond that."

Christie's goals, such as extending the school day and lowering state property taxes, will need strong Democratic support. In his speech, the governor said that "no state has shown more bipartisan cooperation over the last four years than New Jersey" and he urged legislators to "do it again."

State Sen. Kevin O'Toole, a Republican, said that "compromise" is the way governing works in New Jersey and that Christie "knows you need to give a little to get a little."

Christie's Democratic critics acknowledged that he is unlikely to face wrath from a legislature known for its clubby cross-party dealings.

"Christie knows how to exploit power and the way some of the legislators are controlled," Democratic state Sen. Ronald Rice said. "This place is old school. It's about power and big money and he hasn't shaken that up."