Long a bastion of socially conservative, anti-gay sentiment — much of it dating back nearly a decade to gays’ and lesbians’ ultimately unsuccessful effort to march in the annual St. Patrick’s Day Parade — South Boston is undergoing a political metamorphosis, thanks to an influx of young, urban professionals. Recent surveys show that as much as 40 percent of South Boston’s population may have turned over during the last decade, and now even local politicians are forced to pay attention.

Perhaps the best sign of new South Boston voters’ traction is the attention being paid by local elected officials to the campaign to defeat the Defense of Marriage Act (DOMA), which is currently pending before the state legislature. If placed on the ballot and passed by voters, DOMA would prohibit homosexual marriage, civil unions, and domestic-partnership benefits. Last month, Senate president and Democratic gubernatorial candidate Tom Birmingham temporarily derailed the DOMA initiative when, in a highly controversial move, he gaveled a legislative constitutional convention to a close before the issue could be taken up.

In response, a campaign is under way to place DOMA on the 2004 ballot, and conservative Southie state senator Jack Hart was one of many expected to vote in favor of it. But after being lobbied by a half-dozen influential South Boston voters — a group that included South Boston native and city-council president Michael Flaherty — Hart is having second thoughts about the initiative.

" I am as devoutly Christian as anyone ... but we need to be very careful where we go with this issue. I do not want to discriminate against anyone, and some feel [DOMA] will contribute to that, " he told the Phoenix.

Hart’s sensitivity to discrimination notwithstanding, his position may owe more to the growing number of gay and lesbian voters in his district. The Massachusetts Gay and Lesbian Political Caucus (MGLPC) mailing list for Wards Six and Seven (South Boston) shows roughly 900 gay and lesbian voters living there. And since Hart won the seat in February in a special election, legislative redistricting has added most of Dorchester to his First Suffolk District, which now includes large numbers of politically active gays and lesbians, as well as many generally liberal voters.

David Breen, a Democratic activist and openly gay man from South Boston who sits on the MGLPC board of directors, sees Hart’s movement on the issue as part of a trend among South Boston pols.

" It is not bad politics to be in favor of equal rights, " says Breen. " Flaherty has done it with great success ... he even marches in the [Gay Pride] parade. [Stephen] Lynch was elected to Congress supporting civil unions ... even [City Councilor] Jimmy Kelly is loosening up on domestic-partner benefits. "