Ohio's attorney general resigned Wednesday under threat of impeachment because of a sexual harassment investigation in his office and his extramarital affair.

Attorney General Marc Dann, a Democrat elected in 2006 on an anti-corruption platform, said at a news conference that he had to resign to preserve the ability of the office to carry out the priorities he established.

"It is now clear to me that the only way to protect these priorities for the office of attorney general and for the people of Ohio is to remove myself from the situation," said Dann, 46, in Gov. Ted Strickland's ceremonial Statehouse room.

He admitted May 2 to an extramarital affair with an employee that he said contributed to an atmosphere leading to sexual harassment claims against a top aide.

Three aides were forced out in the harassment investigation, which showed managers encouraged a casual work environment with frequent profanity and inappropriate interactions with subordinates.

Dann had resisted resigning, despite demands by Strickland and others within his party, a growing number of investigations into conduct at his office, and the filing Tuesday of articles of impeachment against him.

Strickland, who led the call for Dann to resign or be impeached, said he would begin reviewing possible successors immediately. Under law, First Assistant Attorney General Tom Winters will assume the responsibilities of attorney general until Strickland names a permanent replacement. Voters would need to confirm Strickland's pick on election day, Nov. 4.

An investigation of the attorney general's office under Dann by state watchdog Tom Charles will continue, the governor said. Charles' deputies removed a cart load of computers and files from the office Wednesday.

Politicians of both parties including House Democratic Leader Joyce Beatty said Dann did the right thing by resigning.

"We promised the people of Ohio to end a culture of corruption that existed in the past, and we are fulfilling that promise by cleaning our own house," Beatty said.

Strickland and Dann were among many Ohio Democrats swept into office after an investment scandal that involved a GOP donor and went as high as former Gov. Bob Taft, a Republican.

Copyright 2008 Associated Press