“David said to me, ‘Let me handle it,’” Mr. Baroni continued, then grimaced and closed his eyes. “I listened to him. I have regretted it ever since.”  Mr. Baroni repeated the same answer for five hours, first in direct testimony and then in sometimes scathing cross-examination: I listened to David; it was his project; he lied to me.  “I believed David when he said that, because he spoke for Chris Christie,” he said.  Over eight days on the stand earlier in the trial, Mr. Wildstein described Mr. Baroni as attentive to the details of the scheme, even deciding that the lane closings would start on the first day of school in September 2013 to maximize the catastrophic traffic jam that would — and did — ensue.  For five days of the closings, Mr. Baroni ignored the mayor’s increasingly panicked messages reporting public safety problems, with emergency vehicles and school buses stuck in gridlock. “It’s maddening,” Mr. Sokolich texted Mr. Baroni.  Mr. Wildstein testified that Mr. Baroni delighted in the mayor’s frustration, so much so that his mocking of Mr. Sokolich’s “it’s maddening” became an inside joke. And Mr. Baroni, he said, bragged to the governor about the scheme at a Sept. 11 memorial service, telling him that there were enormous traffic jams in Fort Lee and that Mr. Sokolich’s calls were not being returned.  But taking the stand on Monday, Mr. Baroni, a former New Jersey state senator, told a starkly different story. He said Mr. Wildstein had duped him into believing the lane closings were a legitimate traffic study, one that was important to the governor, and had baldly lied to him that there was no punishment involved.  That belief, Mr. Baroni said, curbed his politician’s instinct to return calls from Mr. Sokolich, with whom he had spent years cultivating a close relationship.  “I listened to David Wildstein when he said to me, if I call the mayor back, that because of my relationship with him, that I would wimp out, give in, and stop, and ruin the study, which was very important,” Mr. Baroni said.  Monday was the first time Mr. Baroni spoke publicly about the lane closings, which ultimately became a scandal that wounded Mr. Christie’s presidential ambitions.  Mr. Baroni did not contradict Mr. Wildstein’s most politically explosive assertion that Mr. Christie knew about the lane closings as they were happening.  But as Mr. Baroni described it, he was more of a functionary at the Port Authority, while Mr. Wildstein was its chief link to “Trenton,” code for the governor. Mr. Christie told Mr. Baroni to hire Mr. Wildstein. Mr. Wildstein did not report to Mr. Baroni, and Mr. Baroni had no power to fire him.  Mr. Baroni, 44, has to give the jury reason to doubt not only Mr. Wildstein, but also Port Authority officials who testified that Mr. Baroni pushed to close the lanes again after New York officials ordered them reopened on the fifth day of the purported study, as well as police officers who said that Mr. Baroni lied and tried to pin the plot on them in testimony to the New Jersey Legislature.  On Monday, Mr. Baroni portrayed himself as a dedicated public servant struggling in vain to control a crisis he barely knew anything about. He had gone to the Port Authority to fix what he called “gridlock” — an ill-chosen word for the situation — between New York and New Jersey officials. He said he was too busy attending to the agency’s $7 billion annual budget to monitor all of Mr. Wildstein’s doings.  Shown a photograph of himself laughing in a small huddle with Mr. Wildstein and the governor at the Sept. 11 memorial — where Mr. Wildstein testified that they had told the governor about the lane closings, then in their third day — Mr. Baroni recalled only that they had laughed about the fact that Gov. Andrew M. Cuomo of New York, a Democrat, was arriving at the ceremony by motorcycle.  “Are you laughing about the Fort Lee lanes?” Jennifer Mara, a lawyer for Mr. Baroni, asked him.  “Absolutely not,” Mr. Baroni replied. As soon as Mr. Sokolich mentioned his suspicions of “punitive overtones” to the shutdowns, on the fourth day of the closings, Mr. Baroni said he demanded Mr. Wildstein tell him if that was true.  “He said, ‘Absolutely not,’ and I believed him,” Mr. Baroni said.  Mr. Baroni also forwarded the message from the mayor to Bill Stepien, Mr. Christie’s campaign manager, believing, he said, that the matter was important to the governor.  On the fifth day, when Patrick J. Foye, the executive director of the Port Authority, who is appointed by Mr. Cuomo, ordered the lanes reopened, Mr. Baroni told him there could be “no public discourse” about the matter. Mr. Foye and his chief of staff testified that Mr. Baroni pushed to close the lanes again.  But Mr. Baroni testified that he was only trying to play peacemaker between Mr. Foye and David Samson, a confidant of Mr. Christie and chairman of the Port Authority board.  “I now have something where the governor of New Jersey has knowledge of, involvement, on a traffic study, an issue that mattered to him,” Mr. Baroni said. “Now I’ve got David Samson, who’s the governor’s best friend, who can’t stand Pat Foye, telling me to go to his office and punch Pat Foye in the face.”  He understood from Mr. Samson and Mr. Wildstein, he said, that he had to persuade Mr. Foye to continue the traffic study, because it was “the governor’s project.”  Lee Cortes, a prosecutor, was accusing and at times incredulous as he began his cross-examination of Mr. Baroni, which will continue on Tuesday.  He played a voice mail message Mr. Sokolich left for Mr. Baroni on the second day of the closings, complaining of chaos in Fort Lee.  “You listened to him,” Mr. Cortes said. “You heard his voice, how he sounded. You knew him. You didn’t call him back? He mentioned these things — ‘total gridlock,’ children getting to school, ‘who’s mad at me’ — you didn’t call him back?”  A version of this article appears in print on October 18, 2016, on page A17 of the New York edition with the headline: Former Christie Aide Says He Was Duped About Bridge Lane Closings. Order Reprints| Today's Paper|Subscribe
Bill Baroni, who is accused of approving the lane closings at the George Washington Bridge, then covering them up, says he was misled by a Port Authority executive.