Last week, Christie fired his deputy chief of staff, Bridget Anne Kelly, after documents emerged showing she had urged one of the governor's appointees at the Port Authority of New York and New Jersey to cause traffic problems in Fort Lee.
Christie also severed ties with his campaign manager, Bill Stepien, who also has been linked to the controversy. Stepien had referred to Fort Lee Mayor Mark Sokolich, a Democrat, as an "idiot" in an e-mail to David Wildstein, a Christie appointee to the Port Authority.
Christie has denied involvement in or knowledge of the plan. He said last week his staff's actions had "embarrassed and humiliated" him.
Wisniewski made clear Sunday "we don't have direct communications that directly go to" Christie. Legislators in Trenton have released thousands of subpoenaed documents that tie members of Christie's inner circle to the plan.
If legislators do learn Christie was involved in the plot, "that raises serious questions that the Assembly ought to look at," including possible impeachment proceedings, Wisniewski said.
He cautioned that his committee's investigation was still in its early stages.
Reince Priebus, chairman of the Republican National Committee, said Christie had demonstrated leadership in addressing the controversy.
"Everyone is fallible," he said on NBC's Meet the Press. "The real question is, What do you do when mistakes happen? He admitted mistakes happened."
Rick Santorum, a Pennsylvania Republican who lost in the party's 2012 primary to Mitt Romney and who is considering running again in 2016, said on Meet the Press: "It's very clear personnel there was not sensitive to what seemed to be a fairly obvious wrong thing to do."