A day after handing out invitations to a mock wedding in front of the Science Center, Harvard’s Bisexual, Gay, Lesbian, Transgender and Supporters Alliance (BGLTSA) heads to the State House this afternoon to lobby for the real thing.

The ideologically-split State Legislature resumes debate today over a proposed Constitutional amendment that would ban gay marriage but provide for civil unions—a debate that stalled when three alternative amendments were defeated last month.

“I think we’re going to have a pretty good following tomorrow for the rally,” said BGLTSA Public Relations Chair Adam P. Schneider ’07, who expects around fifty students at the demonstration on Boston Common.

Members of the Harvard College Democrats also plan to participate in the protest.

“We are for gay marriage and we are for what the [Supreme Judicial Court] ruled,” College Dems President Andrew J. Frank ’05 said, referring to the Court’s decision last November that paved the way for same-sex marriages in the Commonwealth.

In recent weeks, the Dems and BGLTSA have worked to coordinate their efforts in support of gay marriage, according to Schneider, who is also a Crimson editor.

“We’ve had talks with the College Democrats in the past,” Schneider said. “It’s not the first time we’ve coordinated efforts. We have a long-standing relationship.”

The Dems website currently features a video aimed at promoting gay marriage. The two-minute piece, produced by Thomas M. McSorley ’06, the Dems’ legislative director, draws a parallel between the struggle for gay marriage and civil rights battles fought by women and African Americans.

As Radiohead’s “Karma Police” plays in the background, the video warns that President Bush’s call for a Constitutional ban on gay marriage would “write hate into our Constitution.”

Conservative groups on campus do not have plans for today’s legislative proceedings.

The Harvard Republican Club (HRC) will not demonstrate at the State House this week, according to spokesperson Lauren K. Truesdell ’06.

The HRC has taken no official position on the gay marriage issue, she said.

Nationally, Christian groups have mobilized some of the strongest opposition to gay marriage, but officials from several campus Christian organizations, including the Harvard-Radcliffe Christian Fellowship, Orthodox Christian Fellowship and the Harvard-Radcliffe Catholic Student Association, said their respective groups have not planned any events for the week.

In November, the Massachusetts Supreme Judicial Court (SJC) ruled in a 4-3 decision that it was unconstitutional to disallow same-sex marriages in the state.

A HOUSE DIVIDED

In the end, however, the final decision on gay marriage will be made inside the chambers of the State House, not outside on the Common.

“There are a lot of balls in the air right now,” said State Sen. Jarrett T. Barrios ’90, who has been one of the most vocal opponents of the proposed amendments. “Votes will flip…It’s hard to predict what exactly will happen.”

Barrios, who is openly gay and lives with his partner and two adopted sons in Cambridge, received some national attention after delivering an emotional speech to the Legislature during the first round of debates.

“Don’t believe those who tell you that just defining marriage between a man and a woman will not hurt your gay and lesbian friends, your family members, your neighbors and your colleagues, because it will,” Barrios told the Legislature on Feb. 12.

Barrios said that he has received letters and e-mails from Massachusetts college students, but “very, very little from Harvard.” The vast majority of the correspondence is in support of gay marriage, Barrios said.

Plummer Professor of Christian Morals Peter J. Gomes has been active in supporting the SJC’s decision, but has no plans to demonstrate at the State House today. Gomes will, however, appear as a commentator later tonight on New England Cable News.

As of now, Gomes said he has “no clue” what will happen at today’s debate.

“One can never predict the actions of the general court,” said Gomes, who came out as gay in 1991 after a Harvard student magazine devoted an issue to articles criticizing homosexuality.

Gomes also declined to offer any predictions, noting that many people have lost money betting on the machinations of the legislature.

“I am not going to be among them,” he said.

—Staff writer Michael M. Grynbaum can be reached at grynbaum@fas.harvard.edu.