New Jersey Gov. Chris Christie on Tuesday addressed head-on the biggest political crisis of his career when he acknowledged in his State of State address that a politically motivated plot by his aides had done damage to his administration -- but he dwelled on the topic only briefly, training his focus instead on his goals for his second term.

"The last week has certainly tested this administration," Christie, a Republican, said at the top of his speech to a joint session of New Jersey lawmakers.

"Mistakes were clearly made, and as a result, we let down the people we were entrusted to serve," he added. "Our citizens deserve better, much better."

Christie's administration is still reeling from revelations last week that some of his top aides in September shut down access lanes to the George Washington Bridge, the world's busiest crossing, perhaps to punish a Democratic mayor whose town was virtually paralyzed by the gridlock.

A state legislative committee and federal prosecutor have launched separate investigations into the episode.

"Without a doubt, we will cooperate with all appropriate inquiries to ensure that this breach of trust does not happen again," Christie said.

The investigation led by the Democratic state legislature widened this week when lawmakers extended subpoena powers. They plan to target Christie aides involved in the plot, including Bridget Anne Kelly, a deputy chief of staff, and Bill Stepien, Christie's campaign manager.

Christie presided over a two-hour press conference last week to apologize profusely, break with those aides and repeatedly deny he knew anything about their involvement in the scheme.

Many Republicans gave Christie high marks for how he managed the situation, although the controversy still threatens to engulf Christie's hopes to run for president in 2016.

Many questions about the scandal remain, including why the lanes were purposefully closed, how many people in the governor's office were involved and to what extent.

Christie on Tuesday vowed to not let his work be dogged by such questions, even as he cooperates with the ongoing investigations.

"I also want to ensure the people of New Jersey today that this does not define us or our state," Christie said. "This administration will not allow the work that needs to be done to improve the lives of the people of New Jersey to be delayed for any reason."