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.