Authorities have alleged that Weiner exchanged sexually explicit messages with a 15-year-old girl in North Carolina earlier this year.
Weiner is the estranged husband of Huma Abedin, Hillary Clinton's top aide.
Former U.S. Rep. Anthony Weiner pled guilty in a NY federal court on Friday to one count of transferring obscene material to a minor for sexting a 15-year-old girl.
According to the NYT, it was that discovery that led to the late October announcement by since fired F.B.I. director James B. Comey, that the bureau was conducting a new investigation into Mrs. Clinton's handling of official email.
The government is seeking a term of 21 months to 27 months in jail on the single count of transferring obscene material to a minor, though with no mandatory minimum the judge could still give him probation.
Weiner (52) entered his plea before U.S. district judge Loretta Preska shortly after 11am (4pm Irish time).
The New York Times said information about the plea has not been made public but was released by two people who have been briefed on the matter and asked not to be identified.More news: Sergio Aguero and Pablo Zabaleta praised by Man City boss Pep Guardiola
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The controversy over Mrs Clinton's use of a private email server while she was USA secretary of state dogged her throughout the campaign.
Trump fired Comey days later amid the FBI's probe into whether Trump's campaign colluded with Russian Federation to defeat Clinton, an allegation he has vehemently denied.
Weiner cried in court as he apologized to the minor with whom he exchanged the messages. He claimed his account had been hacked but eventually acknowledged he had sent the image as well as inappropriate messages to several women.
Abedin announced her separation from Weiner in August 2016.
Weiner said he began getting mental health treatment in the fall, when he said he "came to grips for the first time with the depths of my sickness". "These destructive impulses brought great devastation to my family and friends and destroyed my life's dream in public service". "And yet I remained in denial, even as the world around me fell apart".
He ran for New York City mayor in 2013 and was leading several polls until it was revealed he had continued his questionable behavior.