Mr. Bowers’s past battles have caused pain. Mr. Hardwick chose to challenge Georgia’s anti-sodomy law in 1982 after police entered his home and arrested him upon finding him engaged in a consensual sexual act with another man.

Ms. Wilde said that Mr. Hardwick died of complications from AIDS in 1991, long before the federal courts would ultimately vindicate his argument that such a law was unconstitutional.

“He died very bitter,” Ms. Wilde said.

That same year, Mr. Bowers withdrew a job offer from a young lawyer, Robin Shahar, when he learned that she had planned to take part in a religious commitment ceremony with her female partner.

At the time, Mr. Bowers said that hiring Ms. Shahar would have lent “tacit approval” to same-sex marriage, which then as now was unrecognized by state law.

Six years later, the federal courts ruled in Mr. Bowers’s favor in a lawsuit filed by Ms. Shahar. Today, Ms. Shahar serves as the adviser on lesbian, gay, transgender and bisexual issues for Mayor Kasim Reed of Atlanta. Reached by phone last week, she was still shaken as she recalled the case and its effect on her life.

But Ms. Shahar also said she “could not imagine a stronger spokesperson to oppose the bill.”

“Michael Bowers is notorious throughout the country for his anti-gay credentials,” she said. “Nobody’s going to question his sincerity when he stands up and says this is the wrong way to do what you’re trying to do.”

The Republican sponsors of the bills, State Senator Josh McKoon and State Representative Sam Teasley, did not return messages seeking comment. But former Gov. Roy Barnes, a Democrat and a longtime friend of Mr. Bowers, said that his participation in the debate would have a big impact.