WASHINGTON (AP) — A Florida politician who emerged as a central figure in the federal investigation into Rep. Matt Gaetz has agreed to cooperate with federal investigators and admits paying an underage girl to have sex with him and other men, according to court documents filed Friday. Joel Greenberg is expected to plead guilty to six federal charges — including sex trafficking of a child — during a court appearance in Orlando on Monday. His cooperation as a close associate of Gaetz signals a significant escalation in the Justice Departmentís investigation and potentially raises the legal and political jeopardy the Florida congressman is facing. Federal prosecutors have been examining whether Gaetz and Greenberg paid underage girls or offered them gifts in exchange for sex, according to people familiar with the matter. The plea agreement makes no mention of Gaetz, who has vehemently denied the allegations and any wrongdoing and has insisted he will not resign his seat in Congress.