Lawyers for former Christie campaign manager Bill Stepien and fired aide Bridget Kelly said in letters to lawmakers that their clients would not cooperate.
Legislators investigating the blocking of traffic lanes near the heavily traveled George Washington Bridge had given the pair until Tuesday to turn over documents after they both originally refused to do so.
Their request that the subpoenas be withdrawn was rejected by state lawmakers, and the new deadline set.
Eighteen other people and organizations close to Christie have complied with similar subpoenas or have been granted extensions to produce documents on a rolling basis. The ongoing scandal threatens to upend any political aspirations for Christie, a Republican who's a possible 2016 presidential candidate.
The panel is seeking to find out from how high up the chain of command the order to block traffic near the bridge came and why the plot was orchestrated. Some believe it was to punish the Democratic mayor of Fort Lee, the town at the base of the bridge, perhaps for not endorsing Christie's re-election bid.
The U.S. attorney's office is conducting a parallel criminal investigation.
Federal officials also are investigating an allegation that the administration tied the receipt of a town's Superstorm Sandy relief funds to its mayor's support for a redevelopment project favored by the governor.
The Christie administration has denied the charges.
Michael Critchely, a lawyer for Kelly, confirmed that his client is not providing documents because the subpoena is "constitutionally defective." He didn't elaborate, but lawyers for both Kelly and Stepien in the past have invoked their clients' rights not to self-incriminate, especially as federal prosecutors are looking into the case.
In a letter Tuesday sent by Stepien lawyer Kevin Marino and obtained by The Associated Press, he asks the panel to explain why it invalidated his subpoena objections, rejects the idea of a private review of documents and says his continuing objections apply to the entire subpoena.
"I can think of no lawful way the committee can obtain documents responsible to its subpoena from Mr. Stepien," Marino wrote. "His principled objections ... raise significant legal issues that are no less valid because they here arise in the context of a politically charged investigation."
Both Kelly and Stepien were trusted Christie aides before the scandal broke. Christie cut ties to Stepien - a day after naming him to lead the state Republican Party - for showing a lack of judgment after the traffic jams happened. Kelly was fired after the investigation erupted into a full-blown scandal last month with the release of messages that showed her saying it was "time for some traffic problems in Fort Lee" in an email weeks before the lane closings.
The eight Democrats and four Republicans in the Legislature who are investigating authorized their lawyer to take legal action to enforce the subpoenas if the pair did not comply.
But on Tuesday, it was Marino who raised the possibility of a court fight.
If the committee refuses to withdraw the subpoena, he suggested "seeking a judicial determination" on the validity of the objections.