ATLANTIC CITY - Hundreds of New Jersey Republicans convened at the Borgata Hotel Casino & Spa here Monday, in what party officials called the largest state GOP gathering in two decades, to begin a campaign to win control of the Assembly in November.

Absent from the event, in a ballroom above the casino, was the state's highest-profile Republican, Gov. Christie, who was in England on a trade mission. He did say in a video message that he would help Republicans' efforts in November and that he was "committed to the furthering of our party's principles and goals in our state."

Christie's absence may have been fitting. The governor formed a federal political action committee last month as he explores a run for president in 2016.

With polls showing waning support for Christie among New Jersey voters, Republicans will have to determine whether they want to hew to the governor's brand or craft a new image.

Every seat in the 80-member chamber is up for election in November. Democrats hold a 48-32 majority in the Assembly and a 24-16 edge in the Senate. One Senate seat, for the Fifth District in Camden and Gloucester Counties, is scheduled for a special election.

"We're beginning the transition to the post-Christie era," Matt Rooney, editor of the conservative blog Save Jersey, said in an interview.

He said the party had begun to coalesce around Assembly Minority Leader Jon Bramnick (R., Union), a close ally of Christie's, who headlined Monday's event.

"There's definitely a sense that Bramnick has stepped up and asserted himself in that leadership role," Rooney said.

Legislative redistricting in 2011 gave Democrats an electoral advantage, and the map will not be redrawn until 2021. There are 700,000 more registered Democrats in New Jersey than registered Republicans.

In the 2013 elections, Democrats retained their 16-seat advantage in the Assembly.

Bramnick told an audience of a few hundred Republicans that he would challenge Speaker Vincent Prieto (D., Hudson) to six debates this year.

"I'm going to tell Speaker Prieto, 'We're coming for you. You may be my friend, but we're coming to take you out.' "

He rejected the notion that Republicans needed to run away from Christie to win in November.

"The problem right now is, the Democrats won't cooperate," he told reporters, so "the governor is having a tough time getting changes done."

In a statement, Prieto spokesman Phil Swibinski said the speaker had "a full plate dealing with the challenges facing working-class residents" and did not "have time for silly sideshows right now."

"If the Assembly Republicans ever come up with some new ideas, he would be happy to hear them out," Swibinski said. "He's glad, however, that Minority Leader Bramnick's comedy career finally really looks to be taking off." (In his spare time, Bramnick is a stand-up comedian.)

Also speaking at the event were former U.S. Sen. Jeffrey S. Chiesa; top Christie political advisers Mike DuHaime and Bill Palatucci; Michael Chertoff, former U.S. secretary of homeland security; and Lt. Gov. Kim Guadagno.

Guadagno called the decade before Christie took office in 2010 "the Democrats' decade of desperation, of disaster and despair."

In addition to calling for lower taxes, tighter spending, and an overhaul of the state Supreme Court-ordered school funding formula, some Republicans hinted they might campaign on another issue: the George Washington Bridge scandal.

Or, rather, the amount of money ($9 million) they accuse Democrats of wastefully spending on an investigation into the September 2013 lane closures.

"You know what we got for that money? We got very clear confirmation that legislators should stick to legislating," said Assemblywoman Amy Handlin (R., Monmouth). "When Democrats turn Trenton into a circus, they are the ones who end up looking like monkeys."

The biggest chunk of that money, about $6.5 million, was spent on legal bills owed to a law firm retained by Christie's office.

aseidman@phillynews.com 856-779-3846 @AndrewSeidman