An aide to Sen. David VitterDavid Bruce VitterPlanned Parenthood targets judicial nominee over abortion comments Trump nominates wife of ex-Louisiana senator to be federal judge Where is due process in all the sexual harassment allegations? MORE (R-La.) resigned Wednesday after reports emerged that he had pled guilty to after an arrest for attacking an ex-girlfriend with a knife.

ABC News reported Wednesday morning that the longtime aide, Brent Furer, pleaded guilty in 2008 to misdemeanor "charges stemming from a knife-wielding altercation with an ex-girlfriend."

According to ABC, Furer has spent the last five years in Vitter's office working, among other things, on women's issues. He also worked on Vitter's last campaign.

The news could hurt Vitter in his reelection campaign against challenger Rep. Charlie Melancon (D-La.) by raising new questions about his attitude toward women. In 2007, Vitter's name was found on the client list for a D.C. escort service. The senator later apologized for the incident.

“The recent announcement that Sen. David Vitter’s embattled aide Brent Furor has resigned is an obvious attempt by the senator to save himself with women voters as he heads into his re-election campaign this fall," Melanie Sloan, executive director of Citizens for Responsibility and Ethics in Washington, said in a statement.

"Sen. Vitter knowingly kept this dangerous person on his staff through his drunk driving arrest in 2003 and his chilling domestic violence assault conviction in 2008 – why have him resign only now?”

Vitter spokesman Joel DiGrado told The Hill that Furer was hired using good recommendations, including those from his military service in Kuwait. In January 2008, he was asked to leave the office pending the charges. After the court issued him a fine and community service, he was allowed to return to Vitter's office after additional disciplinary action.

DiGrado said, however, that the senator was unaware of the other legal issues, which include an open warrant on a Louisiana DWI charge, according to the ABC report.

According to an arrest report posted by ABC, the knife incident happened in an apartment on Capitol Hill. The report said that the woman was stabbed in the hand and also suffered a cut to the chin during the altercation that took eight stiches to close. It said the woman was allowed to leave the apartment after promising not to call the police.

The police report said the couple had been dating for eight months.

Furer plead guilt to misdemeanor charges, including threatening harm and destruction of property. Assault and weapons charges were dismissed. Jail time was suspended, according to ABC.

DiGrado said that the senator did not arrange for legal representation or payment for it. 

This story was posted at 11:09 a.m. and updated at 11:39 a.m. and 12:13 p.m.