Some gambling opponents are hoping to block a sixth casino from being built in Maryland by focusing their energy in one place: Prince George's County.

The county is a key battleground because of a provision in the new gambling law that says the state can build a casino in Prince George's County only if a majority of county voters support it in November — even if the referendum is approved statewide.

That provision, added at the request of Prince George's County lawmakers, essentially gives the county veto power over the new casino allowed by the law, according to the Maryland attorney general's office. While some opponents are skeptical that the provision is ironclad, they still think a strong "no" vote from the county would impose a political hurdle for the next step — securing County Council zoning approval for a casino.

"There will be a vicious fight here, I do believe it," said the Rev. Jonathan Weaver of Greater Mt. Nebo African Methodist Episcopal Church in Bowie. "We will be an epicenter."

Gerron Levi, a former delegate from Prince George's, is organizing a coalition of about 70 county clergy and civic groups opposing the casino. The coalition — called Stop Slots Prince George's County — plans to knock on doors, hold community forums and implore churchgoers from the pulpit to fight the casino.

"People have looked at this as a way to raise money, but they have not looked at this as a predatory industry," Levi said of gambling. "Proximity matters, and my role is to educate people on the transformative impact" a casino would have in the county, she said.

Casino supporters, including Prince George's County Executive Rushern L. Baker III, say they are confident the county will join the rest of the state in supporting the measure.

"We need revenue in the county — we are getting that message out in Prince George's," he said.

Legislation approved by the General Assembly during last month's special session authorizes a sixth casino in Maryland — to be in Prince George's — as well as table games such as blackjack at all six. If a sixth casino is approved, some existing casino license-holders would get tax breaks as compensation for the competition. To take effect, the law must be approved by voters in the November referendum known as Question 7.

The multimillion-dollar fight between supporters and opponents of the measure has so far been waged via television commercials, radio spots and expensive mailers. But both sides say a ground war is looming.

Passions are higher in Prince George's than in many other areas because county residents would experience the most tangible impact from a new casino. Supporters note that the county would get extra financial benefits and many of the jobs. Opponents say the county would more acutely feel the social ills that would come from hosting a 24-hour, Vegas-style casino.

The Washington suburb is in the cross-hairs for other reasons. It is the second-largest county in the state, meaning that both sides are courting county voters because of their sheer numbers.

Supporters point to positive internal polling numbers and recent history: The 2008 statewide referendum allowing slot-machine gambling in Maryland was approved in Prince George's County by 59 percent of the voters.

Opponents, however, have access to something they didn't have four years ago during the initial referendum: cash. In 2008, the money was lopsided, with deep-pocketed gambling interests outspending gambling opponents by an 8-to-1 margin.

This time the casinos are split, with Penn National Gaming — owner of a West Virginia casino that fears Maryland competition — funding a robust ad campaign against a gambling expansion. The company has spent $9.5 million, mostly on commercials in the Washington and Baltimore markets. MGM Resorts, which wants to build the Prince George's County casino, and other like-minded casino interests have put in $9.9 million.

"Usually this is a David-and-Goliath fight," said Levi. "Having Penn National in the fight does help to some degree. It improves our chances."

Her group hopes to "drive up opposition in Prince George's County and defeat it statewide," in part by showing the negative impact a casino would have on the county.

"How does it transform families? How does it transform a community?" she said. "What does that look like in human terms?"

The law says the General Assembly's intent is that a state commission should award a Prince George's license only if a majority of county voters supports the measure.

Levi is skeptical that a "no" vote from Prince George's would legally kill the casino outright, but she believes the County Council would pay close attention to the vote.