Eight years ago, it would have been unimaginable.

But over brunch on a warm Sunday morning last fall, Micah Mahjoubian leaned over and asked his boss a question.

"I told him Ryan and I got engaged to be married, and I'd like him to consider whether he would officiate our ceremony."

John Street, once regarded as Public Enemy No. 1 of the gay community, did not flinch. Yes, he said.

So on Saturday, as the clock winds down on his time as mayor, Street will preside over his first same-sex commitment ceremony, in City Hall.

With 125 guests expected, it will resemble in every way a traditional wedding but will have no legal standing, since Pennsylvania prohibits gay marriage.

Mahjoubian, 33, and Ryan Bunch, 32, will wear matching black tuxedos with orange vests. There will be a 10-person wedding party; each groom's best man happens to be a woman. Mahjoubian and Bunch will say their vows, exchange wedding rings, then leave for a reception at the University of Pennsylvania Museum of Archaeology and Anthropology.

Steven Goldstein, chairman of Garden State Equality, New Jersey's gay civil-rights organization, said he was unaware of another mayor who performed a commitment ceremony in a state where civil unions and gay marriage are illegal.

"Every single time a public official like Mayor Street performs a ceremony," he said, "it strengthens the case for marriage equality."

For Mahjoubian and Bunch, it's as much a political statement as a show of their love before family and friends.

For Street, who has performed fewer than 10 weddings as mayor, it's anything but.

"Micah is my friend. He has been in my campaign and has been in my administration for eight years," Street said. Currently, Mahjoubian is his deputy secretary of external affairs. "I've come to respect him as a person, and if this is something he would like for me to do, then I'd like to do it for him."

But the 64-year-old mayor, a practicing Seventh-day Adventist, was also clear - four times in a 30-minute interview last week - about what the ceremony is not:

"It's not marriage. It's not real marriage. They can't be married. . . . It's not a religious ceremony. I mean, it's not really marriage."

However it's regarded, Street's decision to officiate seems to cap a personal journey of sorts in regard to gay men and women.

Through most of the 1990s, Street as City Council president strongly opposed legislation to provide city benefits to the same-sex partners of city employees. It would cost too much, Street said at the time: "Taxpayer dollars should not be used to support relationships such as these that mimic traditional family relationships."

In 1998, the city did adopt the domestic-partnership ordinance; it was Street's first defeat as Council president.

As he began his mayoral campaign the next year, many in the gay community vilified him, passing out "Stop Street" bumper stickers. It was, Mahjoubian recalled, "anybody but John Street."

The gay community was "right to be apprehensive about me as mayor," Street said. "I had not supported some things that were important to them."

But once elected, many of the same activists said, Street immersed himself in their community.

"He immediately made it clear he welcomed openly gay people serving in his administration. He formed a mayor's commission on sexual minorities. He appointed a member of the community to be a liaison on his staff," said Malcolm Lazin, who in the general election supported Sam Katz, Street's GOP opponent.

As Council president, Lazin said, "he led a somewhat, at least, insular life in terms of interfacing with the gay community. As mayor, I think, he really did want to be the mayor of everyone."

Street supported several gay-related issues - including providing a strong defense of the domestic-partnership ordinance, which a conservative activist was trying to have court toss out.

"By the time 2003 came, people were a lot more comfortable with me as a mayor," Street said.

He declined to elaborate on any personal change he experienced. But some insight into his views was recorded in an e-mail he sent to Mark Segal, his friend and publisher of the Philadelphia Gay News. (The e-mail surfaced after federal agents seized Street's BlackBerrys on Oct. 7, 2003, after an FBI bug was found in his office's ceiling.)

On Sept. 13, 2003, he wrote Segal:

"The past 3 1/2 years have been a great learning experience for me. Thanks to you . . . and many others I have broadened my horizons, expanded my understanding and set aside some bias and prejudices I previously did not even know I had. I have not changed unless you call growing in wisdom and understanding 'change.' "

In his second term, Segal and others said, Street only strengthened his ties to their community. He held an inaugural ball to raise money for Center City's William Way Lesbian, Gay, Bisexual and Transgender Community Center. In 2005, he spoke at an unveiling ceremony for a historical marker at Independence Hall recognizing the work of gay and lesbian activists.

"He turned out to be a better friend to our community than I expected," said Peter Salometo, president of the local Log Cabin Republicans, a gay and lesbian grassroots organization.

While some people might dismiss Street's outreach as political, Segal views his decision to officiate at Mahjoubian and Bunch's ceremony as "from the heart. . . . I think the mayor is doing it out of respect, and in his own mind is making amends for some of the damage he might have created."

Mahjoubian, who in his final bachelor days last week was busy conferring with Street about how the mayor would lead the ceremony, knows it will have no legal meaning.

No matter. "To me, this is like a 'Nixon goes to China' thing," he said. "He came in as a mayor that a lot of people in our community were skeptical of, and yet he is going out able to accomplish more than anyone thought."