By Joseph Ax

NEW YORK (Reuters) - A federal judge rejected a request for a new trial by two former associates of New Jersey Governor Chris Christie who were convicted for their roles in the "Bridgegate" lane closure scandal.

The decision late Wednesday by U.S. District Judge Susan Wigenton clears the way for the two defendants to be sentenced on March 15.

Bridget Kelly, a former deputy chief of staff under the Republican governor, and Bill Baroni, the former deputy executive director of the Port Authority of New York and New Jersey, were convicted in November of orchestrating the shutdown of access lanes at the George Washington Bridge in September 2013.

U.S. prosecutors said the resulting gridlock in Fort Lee, New Jersey, was intended to punish the town's Democratic mayor for declining to back Christie's re-election campaign.

Christie has not been charged in the case and has denied any knowledge of the plan. But Kelly and another conspirator, former Port Authority official David Wildstein, both testified that Christie was aware of the lane closures before they occurred.

Wildstein pleaded guilty and appeared at trial as the government's star witness.

In asking for an acquittal or a new trial, Kelly's lawyers had argued that Wigenton erred when she instructed jurors that they could convict the defendants even if prosecutors failed to prove they had intentionally targeted the mayor for retribution.

The motivation for the scheme, Kelly's lawyers said, was at the core of the government's case.

But Wigenton said motive, while central to the prosecution, is not a required element of the crimes for which Baroni and Kelly were convicted.

"The government was under no obligation to introduce evidence of motive, although motive helps present a coherent narrative of events to a jury," she wrote.

Lawyers for Baroni and Kelly did not immediately respond to requests for comment. They can still ask a U.S. appeals court to overturn the verdict after sentencing has taken place.

A spokesman for New Jersey's chief federal prosecutor, U.S. Attorney Paul Fishman, declined to comment on the ruling.

The scandal's fallout helped sink Christie's once-promising political career. He was passed over for a position in President Donald Trump's administration after his own presidential bid sputtered, and he has seen record-low approval ratings in New Jersey.

(Reporting by Joseph Ax; Editing by Jonathan Oatis)