City leaders in the District of Columbia are expected to approve a gay marriage bill when they meet on Tuesday.

Tuesday's vote is the last stop on a long journey to legal gay marriage in the District that began last spring with passage of a gay-marriage recognition law. The bill's long incubation period has thoroughly aired out detractors' grievances, leaving little room for surprises.

Still, backers are preparing a large rally on Monday.

The show of support is being organized by the Campaign for All DC Families, DC Clergy United and the Human Rights Campaign, the nation's largest advocate for gay rights. Supporters are expected to gather at 7PM for two hours at the Kennedy Recreation Center.

Whether city leaders approve Council member David Catania's gay marriage bill is not up for debate; it will. At a December 1 first reading of the bill, only 2 councilors opposed the legislation: Yvette Alexander and Marion Barry, the District's former mayor. The remaining 11 members voted in favor of the bill.

Yet, obstacles remain. The most immediate is whether Congress – which has final say on laws approved in the District – will move against the bill. Lawmakers have 30 days to respond.

Longtime community activist Bob King believes Congress should act against the bill. He told media sources last week that at least 6 members of Congress have agreed to speak with him on the issue. King appears to be targeting pro-gay rights lawmakers, including Senator Patrick Leahy of Vermont and New Mexico Representative Martin Heinrich. Both men have publicly announced their support for gay marriage.

King is also a member of, the conservative Christian group founded in the spring by Bishop Harry Jackson, minister at the Hope Christian Church in Beltsville, Maryland.

Jackson has become the face of the anti-gay marriage movement in the District. His group is suing to get a question prohibiting gay marriage on the ballot after the city's Ethics Board ruled such a measure would violate the city's Human Rights Act that prohibits discrimination based on sexual orientation.

The gay marriage bill is also opposed by the Catholic Archdiocese of Washington. While the bill would not require religious organizations to perform gay weddings, the church has threatened to shut off programs serving the poor and homeless if the city does not include an exclusion that would allow individuals, including private business owners, to refuse to provide goods and services related to the nuptials of gay couples. Gay activists accused the church of trying to “blackmail the city.” Lawmakers, however, say they are open to a compromise that would keep the archdiocese's Catholic Charities as a city contractor.

Should Congress decide to ignore the issue, gay couples in the District might be reserving wedding chapels as early as January 15.