TRENTON, N.J. -- Republican Gov. Chris Christie, faced with a widening political scandal that threatens to undermine his second term and a possible 2016 presidential run, apologized again Tuesday, saying his administration "let down the people we are entrusted to serve" but the issue doesn't define his team or the state.

On the eve of his second term, he opened his annual State of the State address by touching only briefly on the apparent political payback plot, involving road lane closures that caused major backups at the George Washington Bridge, one of the busiest bridges in the country.

"The last week has certainly tested this administration," he said. "Mistakes were clearly made. And as a result, we let down the people we are entrusted to serve. I know our citizens deserve better."

He received tempered applause after he went on, saying, "This administration and this Legislature will not allow the work that needs to be done to improve the people's lives in Jersey to be delayed."

Christie's measured tone was a noticeable contrast from a year ago when a blustery Christie promised to lead New Jersey back from Superstorm Sandy, the costliest natural disaster in state history.

The scandal broke wide open last week with the release of documents showing Christie aides and appointees orchestrated the Fort Lee lane closings, which delayed emergency vehicles and school buses for hours and infuriated commuters. Democrats believe the scheme was retaliation against the town's Democratic mayor, who didn't endorse Christie for re-election.

After addressing the scandal, Christie moved on in his speech to such familiar themes as avoiding tax increases and working with the Democrats who control both chambers of the state Legislature. But he returned to the theme of bipartisanship throughout as he sought to repel doubts about an aggressive brand of politics that propelled him to the forefront of his party but might also be responsible for an apparent petty political vendetta carried out by members of his inner circle.

"We have succeeded in working together to be an example for the entire country dispirited by partisanship," Christie said. "Let us not abandon that course."

Turning to policy matters, Christie stuck mostly to universal goals such as making communities safer without offering much of a blueprint.

Christie kept plans vague for a key initiative, extending the school day and cutting short summer vacation, which was met with skepticism from Wendell Steinhauer, president of New Jersey's largest and most powerful teachers union and a frequent adversary of Christie.

The union bitterly opposed an overhaul of public employee retirement benefits by Christie and the Legislature in 2011 and spent millions of dollars on anti-Christie ads during his gubernatorial campaigns.

The governor warned that the state in the coming year must reduce its pension and debt service payments, which are scheduled to rise by a combined total of nearly $1 billion.

Democrats oppose the prospects of failing to make promised pension contributions or cutting payouts to retirees.

Christie also promised to present choices to overhaul the state's tax system next month when he presents his budget proposal but did not offer an insight on how he might want to do that. A tax cut he proposed two years ago foundered in the Legislature.

The reception to his ideas from political opponents is likely to unfold as the Legislature gets to work. Democrats may be unwilling to go along with a Republican they sense may have been weakened by the scandal.

As Christie left the chamber after his speech, he tersely shook the hand of the Democrat leading one of several investigations into the scandal, which the governor has denied knowledge of and first apologized for last week. Christie also has fired a close aide, and others on his team have resigned.

Democrats plan to vote Thursday on continuing their investigation.

"Public safety and abuse of power are the No. 1 issues," Democrat Vincent Prieto, the incoming speaker of the state Assembly, said after the speech. "We have to get to the bottom to make sure it doesn't happen again."

Christie's State of the State address and inauguration, scheduled for next week, were intended to launch a second term that's considered a key building block for his political future. After his November re-election, his advisers suggested he had just a one-year window to stack up accomplishments as a can-do, bipartisan leader before his lame-duck status -- and a prospective White House campaign -- start to interfere.

The recent revelations may have slammed that window shut. Though he's not announced plans to run, Christie is an early front-runner for his party's presidential nomination who now is working to rebound from the scandal, the most serious threat to his administration and political ambitions so far.

Unlike previous years, Christie had no live radio or television appearances scheduled for the day after the annual address.