When Maryland legalized same-sex marriage earlier this year, Gov. Martin O'Malley (D) praised his state as a leader on the issue. "I think we all have to step up to it within the context of our own communities and I think some states advance more quickly than others," O'Malley told The Huffington Post's Sam Stein in Feburary.

But a new poll shows that O'Malley may have advanced too quickly for Maryland voters. Released on Wednesday by OpinionWorks, an Annapolis-based polling firm, the survey shows that 43 percent of the respondents favored overturning same-sex marriage, against 40 percent who want to uphold the law.

O'Malley signed the same-sex marriage law on March 1, but opponents have launched a drive to gather the necessary signatures to force a referendum on the law in November. According to the Associated Press, nearly 56,000 signatures will be needed to put the measure on the ballot.

If the drive succeeds, same-sex marriages opponents seem to have greater core support: Thirty-seven percent of voters in the OpinionWorks poll said they "strongly" felt they would vote for repeal, while only 31 precent said the same in favor of the law.

But 16 percent of those polled remain undecided in some form, which, according to OpinionWorks, could be a good sign for those favoring marriage equality. "Those who remain undecided on the referendum tend to be slightly more Democratic and younger, and less religious than the population as a whole -- all groups that lean towards upholding the law," said the firm.

The demographic breakdowns of the poll followed familiar trends on same-sex marriage, with frequent churchgoers, registered Republicans and voters over 65 all favoring repeal in strong majorities. African-Americans also opposed the law by a 48-29 margin. Many black religious leaders in the state had spoken out against same-sex marriage during the debate over passage.

“It is likely that people with the strongest feelings on this issue have already declared themselves, so that the referendum battle will be waged over the small number in the middle who may be coming out to vote in the presidential race, but for whom this issue is not do or die,” said OpinionWorks president Steve Raabe.

UPDATE 10:20 a.m. : An earlier version of this story incorrectly said that 37 percent of poll respondents "strongly" felt they would vote against repeal rather than for it.