Former New York congressman Anthony Weiner will plead guilty to sending obscene material to a minor, US media report.
The charge stems from sexually charged text messages he allegedly exchanged with a 15-year-old girl last year.
He stepped down from his congressional seat in 2011 over a series of sex scandals and was again exposed during his 2013 bid for New York City mayor.
He may have to register as a sex offender and could face prison time.
Mr Weiner is expected to enter his plea at a Manhattan court on Friday morning, according to local media.
He again made headlines during last year’s US presidential election.
During an investigation into the sexting allegation, FBI officials found emails on Mr Weiner’s laptop from his ex-wife, Huma Abedin, who was a top aide to Democratic candidate Hillary Clinton.
An FBI investigation into Mrs Clinton’s private use of email while she was secretary of state was closed after officials said nothing incriminating was found.