The two married in 2010 and in June 2011 Weiner resigned from Congress, a month after the release of an explicit photo of him that he inadvertently posted on his Twitter account.
The hearing will take place at 11 am today, so we'll know more then about any prison time Weiner will get, plus whether and how long he may have to register as a sex offender. According to Weiner's plea, the conduct occurred between January and March.
Weiner reportedly once told the girl, "I would bust that tight p-y so hard and so often that you would leak and limp for a week", and sent her bare-chested pictures of himself.
The probe into his exchanges with the teenage girl, however, also helped upend the final days of the 2016 US presidential campaign.
His sexting scandals not only ended his political career and but they also entangled him in the F.B.I investigation of Hillary Clinton before the election.
Weiner's lawyer, Arlo Devlin Brown, didn't immediately return a message Friday.
As part of his plea, Weiner agreed to forfeit his iPhone. He added that Weiner remains "focused on his recovery".
While investigating the messages Weiner sent, the Federal Bureau of Investigation discovered a trove of emails from Hillary Clinton's private server on his wife Huma Abedin's computer.
That led to then-FBI Director James Comey informing Congress on October 28 that the bureau was again investigating Clinton's private email server use.
The inquiry was brief and Mr Comey announced shortly before the election that the new emails contained nothing to change his view that Mrs Clinton could not be charged with a crime, but she partly blamed her loss to Republican Donald Trump on Mr Comey's announcement.
Federal prosecutors in NY said Weiner admitted to sending sexually explicit photos and "directions to engage in sexual conduct" to a 15-year-old girl. His social media habits continued after leaving Congress and contributed to his poor showing with his 2013 New York City mayoral campaign, a race in which he had once been a leading contender.