He chose to resign rather than be impeached.

Via Washington Examiner:

Gov. Robert Bentley, R-Ala., resigned Monday following a House Judiciary Committee impeachment hearing on allegations that he committed felony-level crimes while covering up an extramarital affair with a female aide, according to multiple local news reports.

Last week, the Alabama Ethics Commission’s “found probable cause to believe” Bentley violated campaign finance and ethics laws while trying to cover up the affair with the aide in 2014. While the committee is still deciding whether to recommend Bentley’s impeachment, the governor’s lawyers are trying to strike a deal that would include him stepping down and pleading guilty to misdemeanor charges.

Bentley’s lawyers represented him during impeachment hearings with the House Judiciary Committee on Monday. Yasamie August, the governor’s spokeswoman, said Bentley was “not personally involved in any negotiations.”

Last year, recordings surfaced of Bentley making sexual comments to an aide while still married. Bentley has apologized for the comments but has insisted he wouldn’t resign.

Lt. Gov. Kay Ivey is expected to be sworn in as governor later Monday. Bentley would have been the first governor in Alabama to be impeached.