ANNAPOLIS — Maryland Gov. Martin O’Malley’s same-sex marriage bill now moves to the state Senate, where floor debate could begin this week, after its narrow passage in the House.
The bill, which would make Maryland the eighth state along with the District to legalize gay marriage, appears to have majority support in the 47-member Senate, which passed the bill last year by a 25-21 vote.
After working furiously last week to gain several crucial votes in the House, supporters in the Senate will mainly have the task of protecting the support they already have.
“It’s a bill we’ve heard before,” said Sen. Brian E. Frosh, Montgomery Democrat and chairman of the Judicial Proceedings Committee, which is expected to vote the bill onto the floor this week. “I don’t think the votes will change.”
The bill passed the Senate during the 2011 General Assembly session, then failed in the House.
Mr. O’Malley, a Democrat, joined House Democratic leaders on Friday night to celebrate the chamber’s 72-67 passage of the bill, which received one more than the necessary 71 votes.
The bill’s passage ended nearly a year of speculation over whether it would have enough votes to pass the House, where many socially conservative Democrats opposed the bill and leading supporters said just weeks ago they were likely three votes short of passage.
The Senate version of the bill is expected to have an easier road, considering none of its 25 supporters from last year has publicly wavered on the issue.
The bill likely still has support from 24 of 35 Senate Democrats and one of 12 Republicans — Sen. Allan H. Kittleman, Howard Republican.
The bill’s Democratic opponents include Senate President Thomas V. Mike Miller Jr., Prince George’s Democrat.
Mr. Frosh said his committee had delayed voting on the bill to gauge its progress in the House. The 11-member panel passed last year’s gay-marriage bill by a 7-4 vote.
The committee typically votes on Thursdays, but could vote sooner at the chairman’s request.
Opponents of the legislation appear resigned to it likely passing in the Senate and but have turned their focus to a repeal-referendum effort.
If the Senate passes the bill, that would give opponents the go-ahead to craft a petition and begin collecting signatures.
They would have until June 30 to collect 55,736 valid voter signatures to suspend the law from taking effect and force a November statewide vote on the issue.
Petition organizers would likely include many of the same GOP lawmakers who led last year’s successful petition against the state’s Dream Act, which would allow in-state tuition for many college-aged illegal immigrants.
“When we take this vote, we will be beginning a process, not ending a process,” said House Minority Leader Anthony J. O’Donnell, Calvert Republican. “The citizens of Maryland will have the final say.”