A spokesman for New Jersey Governor Chris Christie has told investigators his boss had no previous knowledge of a deliberately engineered traffic jam on a busy bridge to New York City.
Michael Drewniak called the plot "reckless" in a statement to a New Jersey legislative committee.
Democrats are overseeing the latest inquiry into the incident in September.
Republican Mr Christie has said the scandal hurt his standing for his party's 2016 presidential nomination.
The legislative committee inquiry has reportedly been stymied after two people refused to co-operate and a third refused to testify.
The panel earlier heard testimony from former Christie employee Christina Renna, who said Bridget Kelly - a Christie aide dismissed over the incident - would not have caused the traffic jam on the George Washington Bridge without orders to do so.
The incident is also being investigated separately by the US attorney's office for New Jersey - a federal law enforcement office that reports to President Barack Obama's justice department - though the scope of that inquiry is not yet clear.
Mr Christie has seen his approval ratings sink after his senior aides and confidants were implicated in the four-day traffic jam in the streets of Fort Lee, New Jersey.
The gridlock happened when the Port Authority of New York and New Jersey closed local lanes leading from Fort Lee streets onto the George Washington Bridge, ostensibly for a traffic study.
Publicly released documents have indicated the incident was orchestrated by Mr Christie's aides, possibly to punish Fort Lee's Democratic mayor for his refusal to endorse the governor in his 2013 re-election campaign.
Mr Christie subsequently fired deputy chief of staff Ms Kelly for her role in the matter. David Wildstein, an official at the transit agency and Christie confidant, was forced to resign.
In March, a law firm hired by and with close ties to Mr Christie released a report clearing him of wrongdoing in the scandal.