By Alice Popovici
ANNAPOLIS, Maryland (Reuters) - Maryland's governor plans to sign a bill making same-sex marriage legal later this week, his office said on Monday, while opponents were making plans to challenge the new law at the ballot box.
The legislation, making Maryland the eighth state in the nation to legalize gay and lesbian nuptials, heads to Governor Martin O'Malley's desk for his signature at a ceremony at 5 p.m. on Thursday, his office said.
The Democratic governor has supported the measure and promised to sign it once it was passed by lawmakers. The state Senate voted in favor of the bill last week after it was passed by the state's lower House of Delegates.
While still controversial, same-sex marriage has been gaining acceptance nationally in recent weeks as Washington state legislators voted to allow gay marriage and the New Jersey legislature passed a gay marriage law through both houses, although it was vetoed by Governor Chris Christie.
An appeals court has also overturned California's ban on gay marriage, enacted through a 2008 ballot initiative.
Same-sex couples can marry in the District of Columbia and in six states -- Massachusetts, Iowa, Vermont, New Hampshire, Connecticut and New York. Washington state will join the list in June unless opponents stop it ahead of a possible ballot initiative.
Opponents of same-sex marriage in Maryland were working to get a referendum seeking to repeal the law on the ballot in November.
"The citizens of the state, since it's such a weighty issue, should have a final say," Republican Delegate Tony O'Donnell, the House minority leader who opposed the bill, said on Monday.
"All polling data shows that the state is closely divided on this issue," O'Donnell said. The Senate passed the bill 25 to 22; the House approved it 72 to 67.
Asked about the push for a referendum, the governor's spokeswoman Takirra Winfield said the effort was not unexpected.
"The governor has faith in the people of our state," she said, adding that the governor believed voters will "seek to take the best action that will protect equality for all."
Opponents would need nearly 56,000 signatures to get the measure on the ballot, according to the Maryland State Board of Elections. They would need to submit a third of those signatures by May 31 and the remainder by June 30 to get the measure on the November ballot.
(Editing By Ellen Wulfhorst and Cynthia Johnston)