ST. LOUIS — The former top elected official in Missouri's largest county will plead guilty to corruption charges, federal prosecutors in St. Louis said Thursday.

The U.S. Attorney's office announced former St. Louis County executive Steve Stenger's hearing for the guilty plea will be at 10:30 a.m. Friday. A spokeswoman said the Democrat will plead guilty to all charges in the indictment that was announced Monday — bribery, mail fraud and theft of honest services.

Stenger's attorney, Scott Rosenblum, would confirm only that a hearing is scheduled and declined further comment. Stenger could face up to 20 years in prison on each count.

The indictment accused Stenger of trading political favors for campaign contributions. Stenger was elected to his second term as county executive in November. He resigned within about an hour of the indictment.

Interim County Executive Sam Page, a Democrat, said in a statement that the swift resolution of the case was "proof that the justice system works.

"Mr. Stenger betrayed the trust that St. Louis County residents placed in our government," Page said. "I am committed to reforming County government so that pay-to-play politics never infects it again."

Stenger, 47, was accused of ensuring that donor John Rallo and his companies — Cardinal Insurance and Cardinal Creative Consulting — obtained contracts with the county and received other favors. Stenger also is accused of ensuring that an unnamed company obtained a state lobbying contract from the St. Louis Economic Development Partnership, and taking actions to conceal the illegal conduct.

The U.S. attorney's office said Stenger sought to "secretly use his official position to enrich himself through soliciting and accepting campaign contributions from individuals and their companies in exchange for favorable official action, and for individuals and their companies to enrich themselves and their companies by secretly obtaining favorable action for themselves and for their companies, through corrupt means."

The voicemail on a phone for Rallo was full and not accepting messages. Federal prosecutors have declined to say if Rallo might face charges, saying that the investigation is ongoing.

Investigations by the St. Louis Post-Dispatch raised concerns about county contracts going to Stenger's political donors. The St. Louis County Council began an ethics investigation that included asking state and federal investigators to look into the county's lease of office space at a renovated shopping mall owned by developers who gave $365,000 to Stenger's campaign.

Stenger has previously denied wrongdoing.

In January, the St. Louis Economic Development Partnership's board of directors forced out Sheila Sweeney, who was appointed by Stenger to run the partnership. Her removal followed Post-Dispatch investigations that, among other things, raised questions about its procurement practices and the awarding of contracts to Stenger's campaign donors.