Gov. Chris Christie's chief of staff is set to go before a New Jersey legislative committee investigating traffic jams at the George Washington Bridge.
Kevin O'Dowd is due to testify under oath Monday.
The panel hopes to gain more information about who in Christie's circle ordered traffic diverted near the bridge to create gridlock in the town of Fort Lee to punish the mayor.
O'Dowd told lawyers hired by Christie that he had no knowledge of the plot. O'Dowd said he learned in January -- four months after the lanes were blocked for four days -- that ex-staffer Bridget Kelly put the scheme in motion.
Christie, who is considering running for president, has denied advance knowledge of the scheme.
O'Dowd is Christie' nominee to be the state's next attorney general.