Groups campaigning for and against an expansion of gambling in Maryland, which would allow a Prince George's County casino, have released new ads as casino developers sink millions of dollars into efforts to protect their interests.

Penn National Gaming, the owner of Hollywood Casino Perryville, Rosecroft Raceway and Hollywood Casino at Charles Town Races in West Virginia, registered a committee called Get the Facts -- Vote No On 7, and kicked off a statewide television ad urging residents to vote against the gambling ballot question, which would authorize the state's sixth casino site and allow table games at all existing casinos in Maryland.

Voters statewide must approve the measure, and legislation passed by the General Assembly in August includes a provision designed to prevent a Prince George's casino without approval by county voters.

The Get the Facts' ad and website suggest lawmakers and casino officials may have forged backroom deals to ensure a casino will come to National Harbor, the site preferred by Prince George's County Executive Rushern Baker.

Penn National's Rosecroft in Fort Washington also could bid for a Prince George's casino.

"This ad is only the beginning of a serious effort to inform Maryland voters on the consequences of the proposed gaming expansion," said Jacqueline Goodall, chairwoman of the committee and mayor of Forest Heights in Prince George's County. "The costs of another casino in Maryland exceed the benefits, and voters do not deserve to be misled by false promises and misinformation."

Penn National also wrote an open letter in print advertisements reminding voters of the company's contributions to the state's gambling and horse racing industry -- efforts they say are being ignored by a bias toward a casino at National Harbor.

Penn National isn't new to fighting gambling expansions that threaten its profits in nearby states. In 2008, the company spent $37.9 million to drum up votes against plans to allow a casino in Ohio.

MGM Resorts International, which has agreed to build a casino at National Harbor with the Peterson Cos. should the ballot question pass, has already sunk $2.4 million into a pro-ballot group, For Maryland Jobs and Schools.

Howard Libit, the committee's spokesman, said Penn National is trying to protect its West Virginia profits.

"This is a West Virginia-funded effort to deceive Marylanders and deprive them of the thousands of jobs and millions for our schools that a new world-class resort casino would bring to the state," Libit said.

For Maryland Jobs and Schools kicked off its own television ad last week, touting 4,000 new permanent jobs and the additional $100 million a year a new casino will help draw for education spending in Maryland. The AFL-CIO labor federation and the Baltimore Building & Construction Trades Council union have thrown their support behind the National Harbor casino.