WASHINGTON - New Jersey Democrats are on the offensive against Gov. Christie.

But as they take aim at Christie and his aides over the September closure of two lanes leading to the George Washington Bridge, some Democrats have questioned why it has taken so long to stand up to the Republican star.

To them, the sharp questions of the last two weeks have been too long coming - and slowed by their own leaders.

"None of this would have happened unless there were lapdogs on the Republican side and enablers on the Democratic side, so let's not kid ourselves," said U.S. Rep. Bill Pascrell (D., N.J.). The combination, he argued, created a culture in which the administration believed it could "get away with anything."

Pascrell, a fiery liberal whose district includes Fort Lee, the borough hamstrung by traffic after the lane closures, would not name specific Democrats.

"I'm talking about those who went out of their way to spit in the eye of our own candidate," he said, referring to lack of support for Christie's Democratic gubernatorial opponent, Barbara Buono. "These are enablers. . . . Many of them were there for four years for the governor."

Pascrell's comments point to tension that has long simmered among Democrats as Christie became the dominant force in state politics and established himself as a front-runner for the 2016 GOP presidential nomination, in large part by capitalizing on alliances across the aisle and playing up his bipartisan appeal.

Though some Democrats have embraced cooperation with the governor - and enjoyed the political spoils - others have chafed at what they see as a too-cozy relationship.

The investigation into the bridge scandal has brought out new aggressiveness from Democrats, but some expressed lingering suspicions about how far and how forcefully their leaders will push, especially after they saw Christie's Democratic allies as being slow to embrace the fight.

"There's a faction of Democrats that are really ready and willing to go after the governor, and then there's a faction that feels more ambivalent about this," said Monmouth University pollster Patrick Murray.

Until now, the party's most influential figures have largely opted for collaboration with the governor, spawning a derisive label from their critics: "Christiecrats."

Christie's top Democratic supporters have included State Senate President Stephen Sweeney of Gloucester County; U.S. Sen. Cory Booker, one of the best-known Democrats in the country; Essex County Executive Joseph DiVincenzo, North Jersey's most potent political operator; and South Jersey power broker George E. Norcross III, a close Sweeney supporter, power in statewide politics, and co-owner of The Inquirer.

"We were swallowed up as a party by Gov. Christie's bully pulpit," said Elizabeth Mayor Christian Bollwage, one of more than a dozen Democratic officials and operatives interviewed for this article. "The leadership [in Trenton] has always been with the governor."

But Bollwage said the revelations about the lane closures uncovered thus far by Assemblyman John Wisniewski (D., Middlesex) had shown "a chink in the armor of the governor" that would embolden Democrats.

Until now, Christie has steamrollered all opponents. One of his greatest strengths has been his ability to push and pull lawmakers along with him - unlike his predecessor, Democrat Jon Corzine, who fumbled with the levers of power.

Democrats and Republicans who support Christie get their phone calls returned, state aid for their beloved projects approved, and chances offered to stand alongside the governor in photo ops.

Christie gets to burnish his national credentials as a pragmatic Republican with a record of electoral and governmental success in a deep-blue state.

DiVincenzo endorsed Christie's reelection bid last year. Norcross and Booker made high-profile appearances with him in the midst of the campaign, lavishing him with praise ("guv love," Booker called it) while officially backing Buono.

Despite their cooperation on some issues, Sweeney said, he has supported the bridge investigation "from day one."

His second-in-command, Senate Majority Leader Loretta Weinberg (D., Bergen), has been one of the leaders on the inquiry, and she took charge in the Senate because the scandal unfolded in her district, Sweeney said.

"I've had her back, and she has kept me in the loop from the very beginning," he said. "Not one time did we say, 'Don't do this' or 'Don't do that.' "

He called any suggestion otherwise "insulting."

On Saturday, Sweeney quickly branded as "extremely disturbing" new accusations leveled by the Democratic mayor of Hoboken that the Christie administration was holding Hurricane Sandy aid to the city hostage for political reasons.

Sweeney and Assembly Majority Leader Lou Greenwald (D., Camden) pointed out that Democrats have bucked Christie on key issues such as same-sex marriage, a proposed income tax cut, and court appointees.

But they and other Christie allies, including Booker and DiVincenzo, also said they had to work with the governor to help their communities and to make progress on issues where they share common ground. The bipartisan results, including reforms for public employee pensions and a property-tax cap, provide a stark contrast with a gridlocked Congress.

"I'm not going to fight just to fight," Sweeney said.

One Democratic aide described those looking for more anti-Christie partisanship as the party's own version of a "tea party wing." Others warned that partisan overreaching in the investigations would backfire.

"New Jerseyans don't care about politics," said Booker, former mayor of Newark. "They care about getting things done for people."

Booker has said little about the scandal. A public statement called the damaging e-mails "deeply troubling" but did not mention Christie by name.

Still, the e-mails detailing Christie aides' role in the lane closures - including the now-famous message that it was "time for some traffic problems in Fort Lee" - have given the issue such momentum that no Democrat can afford to resist the investigations, Murray said.

If more major revelations emerge, he said, the party's future gubernatorial hopefuls "can't be seen as having tried to protect the governor."

Some of the differences, of course, are political: Among the Democrats jockeying to run in the next governor's race are those staking out positions as bipartisan collaborators (Sweeney) or true-blue Democrats (Jersey City Mayor Steve Fulop).

Some friction comes from the inevitable scramble for attention and credit on a national story.

And some is just a natural state for New Jersey Democrats, a fractious group even in their best times.

Pascrell, the North Jersey congressman, said many Democrats and Republicans genuinely wanted to get to the bottom of the lane closures. But others in both parties, he said, "want it to remain exactly like it is, because they bathed in it for four years."

As investigations gained steam last week, he was asked whether Democrats were now on the same page.

He replied, "They'll pretend to be."