The campaign manager for Secretary of State Cathy Cox resigned on Wednesday amid allegations that he altered an online biography of her Democratic opponent to add a mention of his son's arrest in a fatal drunk driving accident.

Cox said an internal investigation confirmed that the posting about her opponent, Lt. Gov. Mark Taylor, on Wikipedia, a popular online encyclopedia, came from within her gubernatorial campaign.

"My campaign manager Morton Brilliant, who is responsible for all the work in my office, has offered me his resignation and I have accepted it," Cox said in a statement.

Cox apologized to Taylor and his family.

"From the very day I learned of the Taylor family tragedy, I laid down the law with my staff and supporters: This personal matter would have absolutely no place in my campaign, whatsoever," Cox said.

"Today, I have once again made it clear to my staff that personal attacks, especially on the family members of candidates, are completely off limits."

The shakeup in Cox's campaign comes a day after Taylor's camp first alleged that Brilliant had doctored Taylor's Wikipedia entry to add information on Fletcher Taylor's August 2005 drunk driving arrest in Charleston. S.C.

Fletcher Taylor is awaiting trial on charges stemming from that crash, which left his best friend dead.

Taylor spokesman Rick Dent called for Brilliant to be fired, saying a trace of online traffic showed that the revisions came from Brilliant's computer.

"The Taylor family appreciates Cathy Cox's words and we hope now this will be the end of personal, gutter politics in this campaign," Dent said Wednesday.

The Taylor campaign had provided documents showing that the same online server that revised Taylor's profile tinkered in the same month with biographies on races in Washington state and South Carolina. Brilliant worked on both contests.

Cox has stressed ethics in her campaign and said he would not resort to politics as usual in her bid to become Georgia's first female governor.

Brilliant's resignation plunges the Cox campaign into uncertainty with less than three months to go before Georgia's July 18 primary.

The Cox campaign has struggled to find its footing recently.

An attempt to show that Taylor's first television advertisement exaggerated his role in creating the HOPE scholarship fell flat. One of the state lawmakers the Cox campaign enlisted to undercut Taylor's camp ended up supporting him.

And the Wikipedia flap overshadowed what had been billed as a major policy address by Cox at the YMCA in Atlanta on Wednesday.

In that speech, Cox called for "a new covenant with the people of Georgia." As governor, Cox said she would invest heavily in classrooms to improve the schools' lackluster academic performance.

She also laid out initiatives to make health care more affordable, including allowing the uninsured to band together to purchase coverage, expanding access to PeachCare and lowering prescription drug costs.

Cox and Taylor are battling for the Democratic nomination to challenge Republican Gov. Sonny Perdue.

Perdue on Wednesday cast himself as being above the fray as he signed into law a bill cracking down on sexual predators.

Perdue said it was "silly" that a reporter would ask him about the Democratic infighting.

"The people of Georgia could give a flip about this squabbling," he said.