Washington (CNN) - The nation's capital city is expected to take a major step Friday towards legalizing same-sex marriage.
District of Columbia Mayor Adrian Fenty is scheduled to sign a measure that would recognize gay marriages as legal. The city council overwhelming passed the bill on Tuesday, following a similar vote on December 1.
According to Fenty's schedule, posted online, the mayor will perform the signing at All Souls Church, a Unitarian house of worship in the northwest part of the District that is known for its diversity and for the welcoming of same-sex couples.
Following the mayor's signing of the legislation, the measure goes to Congress for a 30-day review period, but it's considered unlikely that the Democratic majority on Capitol Hill will block the bill. By law, Congress has the right to review and overturn laws created by the District's city council.
If the measure becomes law, the District would join Massachusetts, Connecticut, Vermont and Iowa in allowing legal same-sex marriages. A law legalizing gay marriage in New Hampshire takes affect on January 1.
Earlier this year, lawmakers in Maine approved a measure legalizing same-sex marriages, but voters in the state last month passed a referendum to overturn the new law. Last week, New York's state senate defeated a bill that would legalize gay marriages. A similar bill stalled last week in New Jersey's state senate.
Tuesday's vote in the nation's capital prompted approval from gay rights groups. The Human Rights Campaign applauded the passage of the legislation, calling it a "a victory for all D.C. residents."
"The legislation the Council passed today reinforces the legal equality and religious freedoms to which all D.C. residents are entitled," the organization's president, Joe Solmonese, said in a written statement.
The National Organization for Marriage, which opposes same-sex marriage, said "the fight is not over."
"Politicians on the city council are acting as if they have the right through legislation to deprive citizens of D.C. of their core civil right to vote, but we will not let them get away with it," said Brian Brown, the organization's executive director.
"We will go to Congress, we will go to the courts, we will fight for the people's right to vote," he said.
Opposition to the legislation also came from Catholic Church's Archdiocese of Washington, which has said that the measure could restrict the church's ability to provide charity services, apparently because the church might cut back on services rather than comply with requirements.
CNN Deputy Political Director Paul Steinhauser contributed to this story
Follow Paul Steinhauser on Twitter: @psteinhausercnn