An upcoming referendum on gay marriage in Maryland is threatened by a gambling proposal, marriage equality supporters say.

Maryland lawmakers approved and Governor Martin O'Malley signed a measure legalizing gay marriage earlier this year. The law won't take effect until January 1, 2013, giving opponents sufficient time to attempt to repeal the law at the ballot box in November.

O'Malley is also backing a proposal to open the state's sixth casino to be built in conservative Prince George County and is expected to introduce a draft bill to lawmakers on Friday. If approved during a special session, voters would decide on the measure in the fall.

“Gambling overwhelms every issue in the state,” Chrys Kefalas, former legal counsel to former Governor Robert L. Ehrlich Jr, told The Washington Post. “This is a big fight with the potential for collateral damage.”

A gambling measure on the fall ballot “will energize a base of opponents who would also vote against marriage equality at a time of soft support for marriage equality,” he added.

Jeff Krehely, vice president for LGBT research and communications at the Center for American Progress, agreed: “Any campaign to defeat a new casino might entail religious opponents to gambling coming out of the woodwork.”