TRENTON -- The co-chair of the Legislature's committee investigating the Bridgegate scandal is demanding the panel's own lawyer refund $1 million to taxpayers, saying the high-profile legal firm had a conflict of interest.

And both leaders of the panel told NJ Advance Media they intend to replace the Chicago-based Jenner & Block as their special counsel if lawmakers reopen their probe into the George Washington Bridge lane closings.

Senate Majority Leader Loretta Weinberg (D-Bergen) said she wants Jenner & Block to refund all fees to taxpayers from its work for the Legislature's Joint Select Committee on Investigation because the firm began defending United Airlines last year in a federal criminal investigation of former Port Authority chairman David Samson.

The Legislature's panel focused on politically motivated lane closures on the George Washington Bridge, which is operated by the Port Authority. Legal experts say the law firm may have violated state and American Bar Association conflict of interest rules by taking on United as a client.

"It's only in New Jersey that we get in this morass, but we couldn't even count on the people representing us," said Weinberg.

Her co-chair, Assemblyman John Wisniewski (D-Middlesex), who on Tuesday announced he is running for governor in 2017, said "if they've broken the rules ... then it's appropriate that they should disgorge" their legal fees.

Lawmakers want to target Christie

The demand that Jenner & Block refund taxpayers is the latest in a series of Democratic attacks sparked by the Bridgegate trial's guilty verdicts.

Last month, Weinberg called for the New York-based firm Gibson Dunn & Crutcher to refund the $8 million the Christie administration paid for a March 2014 report exonerating the governor after federal court testimony contradicted its findings.

And last week, she called on Assembly Speaker Vincent Prieto (D-Hudson) to initiate impeachment proceedings against Christie for his alleged involvement in Bridgegate.

Jenner & Block partner Reid Schar, the former federal prosecutor who'd helped put Illinois Gov. Rod Blagojevich behind bars for soliciting bribes for political appointments, did not return several requests for comment.

Jenner & Block partner Katya Jestin, who served as co-counsel on United's non-prosecution agreement with the U.S. Attorney, declined comment.

The law firm was first hired in early 2014 as special counsel to an the Assembly Transportation Committee chaired by Wisniewski to look at the Port Authority's role in the Fort Lee access lane closures in September 2013, later revealed to be an act of political retribution against the town's mayor for not endorsing Gov. Chris Christie's re-election.

The firm was retained when the investigation into the lane closures was transferred to a joint Senate and Assembly committee co-chaired by Wisniewski and Weinberg.

But late in 2014, just as the committee's investigation was wrapping up its interim report, United Airlines became a target in a federal criminal investigation into Port Authority chairman Samson, according to a source with knowledge of the case who was not authorized to speak publicly about the matter and requested anonymity.

While negotiating with the Port Authority for a new hangar and lower fees at Liberty International Airport, United began operating a money-losing route from Newark to a South Carolina city close to the Port Authority chairman's home starting in September 2012, at Samson's request.

Samson had also been subpoenaed by the Legislature's committee in 2014 for his role in the Fort Lee access lane closures, but he invoked his Fifth Amendment rights against self-incrimination and declined to produce any material to the committee except for his phone logs.

In March 2015, Jenner & Block informed the Legislature's committee that it had signed a new client who'd been subpoenaed by the U.S. Attorney in a Port Authority investigation. The law firm didn't disclose the name of the subpoenaed client, citing attorney/client privilege.

On July 11, 2016, Jenner & Block secured a non-prosecution agreement with the U.S. Attorney in New Jersey on behalf of United Airlines in exchange for the airline's cooperation and a $2.25 million fine.

The signatures of two Jenner & Block managing partners on that agreement confirmed for the Legislature's committee that United was the previously unnamed recipient of a subpoena in a federal Port Authority corruption probe, according to Weinberg.

Samson pleads guilty in airline shakedown

Three days later, Samson pleaded guilty to a single federal felony count of bribery for accepting a weekly United flight to a city near his South Carolina vacation home.

"Knowing what we know today, the optics are horrible," said Wisniewski.

In its March 2015 letter to executive directors of the Assembly and Senate Democratic majority offices informing them the firm was representing another client, Schar argued there wasn't a conflict of interest because the federal subpoena "does not involve the closure of access lanes at the George Washington Bridge, and is therefore not encompassed by the Committee's current investigation."

In the letter, Schar noted that the representation of his firm's other subpoenaed client began "after the Committee's transition to hiatus and after our provision of the interim report to the Committee."

And he added that his firm had "erected an ethical wall between our investigation on your behalf and our representation of the other client" -- since revealed to be United Airlines -- and sought to get the investigative committee to confirm that Jenner & Block should "resume our investigation on behalf of the General Assembly and the Senate when and if that's possible."

Neil Mullin, a partner in the Montclair-based SmithMullin law firm and an expert on employment contract law, said if Jenner & Block was on opposite sides of issues related to the Port Authority, it might have violated both New Jersey's Rules of Professional Conduct for attorneys and a virtually identical rule at the American Bar Association on conflict of interest.

"The law is very clear on this," said Nancy Smith, a partner in SmithMullin. "It says you cannot switch sides, ever. And the penalty is disgorging all the profits gained by doing so."

Richard Painter, who served as chief ethics lawyer to the White House under President George W. Bush, said Jenner & Block's contention that there was no conflict because the other client's subpoena did not involve the George Washington bridge lane closures ignored the fact that the committee wasn't set up to investigate only that.

"You can't ignore the other aspects of corruption at the Port Authority to focus only on the lane closures," Painter said. "The committee was charged with investigating corruption throughout the Port Authority."

Weinberg: Christie-hired lawyers should refund $8M

Mullin, who recently won a $20 million sexual harassment settlement against Fox News for former anchor Gretchen Carlson, said there's a reason for the conflict rules.

"You learn confidences when you represent the other side," he said. "You learn how they're thinking, strategically, and can say, 'We know how the Legislature thinks about this, so we can better advise you.' I mean, it's incredible what they've done. Can you imagine if the Legislature were now to haul (ex-United Airlines CEO Jeff) Smizek or Samson before them? Jenner would be operating in a schizophrenic fashion."

Weinberg said that if she had known her special counsel had started representing United, she would have immediately severed ties with the firm.

Wisniewski said that with 20/20 hindsight, he would have made "a different decision" about keeping Jenner & Block on as special counsel.

Before becoming special counsel, Jenner & Block was paid $750,000 for its work helping Democrats draw legislative districts favorable to the party in 2001 and 2011. Wisniewski, then state Democratic chairman, hired the firm for the 2011 redistricting fight.

Weinberg said Jenner & Block was "very passive" about the sort of counsel they provided her investigative committee.

"I wasn't big fans of theirs," said Weinberg, who said she'd hoped Jenner & Block's Schar would draw heavily on his expertise as a former federal prosecutor to help guide legislators who were inexperienced at marshaling evidence and issuing subpoenas. "We didn't get that guidance."

Wisniewski said he wishes he'd gotten "more aggressive" counsel about whom to subpoena from Jenner & Block.

Now that former Christie allies Bill Baroni and Bridget Anne Kelly have been convicted by a federal jury for their roles in the lane closures, Weinberg and Wisneiewski say they want to revive their investigation with a new special counsel, noting that several witnesses who gave sworn testimony before their committee offered conflicting accounts to federal prosecutors during the Bridgegate trial.

"The public has a right to know who was lying to us, and for what reason," said Wisniewski.

Senate President Stephen Sweeney (D-Glouchester) and Assembly Speaker Vincent Prieto (D-Hudson) will have the final say on reviving the investigation.

Claude Brodesser-Akner may be reached at cbrodesser@njadvancemedia.com. Follow him on Twitter @ClaudeBrodesser. Find NJ.com Politics on Facebook.