David Williams, president of the organization, said he "does not discuss donors." He said the group's opposition to gambling expansion in Maryland is consistent with its anti-corporate welfare position because current casino owners would receive tax breaks to compensate them for the enhanced competition.
David Cordish, who owns the Maryland Live casino and strongly opposes a casino at National Harbor, said he is not funding the group.
Another deep-pocketed company that is opposed to a new casino at National Harbor is Penn National Gaming Inc. The company's racetrack and gambling site in Charles Town, W.Va., brought in nearly $197 million in the past 12 months and could lose some of its Washington and Virginia gamblers to a new casino.
Eric Schippers, a spokesman for Penn National, would not say whether his company has written any checks for the commercials. "As a policy matter, we don't comment on fishing expeditions," he said when asked about the company's role in financing commercials.
But corporate leaders have sent a clear message to Gov. Martin O'Malley. Penn National CEO Peter M. Carlino wrote to the governor in late July, pledging to "fight furiously to stop this rush to create an exclusive opportunity for National Harbor."
Carlino, who sits atop the $2.8 billion firm, said he would wage the battle "to the limits of our corporate resources."
Three years ago, Penn National spent about $38 million in Ohio to defeat a ballot initiative that would have allowed a new casino — one that threatened its existing facility in Indiana.
Penn National also has spent heavily in Maryland. It shelled out $2 million to support the creation of Maryland's gambling program in 2008. Then it successfully bid to build a slots parlor in Cecil County.
In 2010, a group partly owned by Penn National spent $7.4 million on an Anne Arundel County campaign in an attempt to stop Cordish from building the Maryland Live casino. (County voters allowed the casino to go forward.)
The Taxpayers Protection Alliance's commercial suggests that the state would "create a secret commission" to give "tax bailouts for casinos."
To back up the assertion, it makes reference to a Baltimore Sun blog post that quotes O'Malley as saying that top lawmakers were coalescing behind an idea for a commission that would have a role in setting tax rates for casino operators. The governor has yet to offer a formal proposal for such a commission.
A third group, which has placed a single ad buy, is the Prince George's County Contractors Association. Its ad, no longer running, linked MGM Gaming — the group that would run a casino at National Harbor — to what it called "organized crime."
That allegation refers to MGM's decision to sell its share of an Atlantic City casino rather than terminate its partnership in Macao with Chinese businesswoman Pansy Ho. A New Jersey board found her to be "unsuitable" as an operator because of her father's alleged ties to Asian crime gangs.
MGM Chief Executive James J. Murren noted that he never had the chance to formally rebut the allegations in New Jersey. He said the Nevada casino commission, looking at essentially the same facts, approved the partnership.
The impact of these summertime television and radio ads is difficult to gauge. A number of lawmakers said they'd heard from constituents about the casino issue, but said the comments seemed to be mostly generated by news coverage and editorials, rather than the television commercials.
Sen. Edward R. Reilly, an Anne Arundel County Republican, called the commercials "self-serving."
"Everybody hates 'em," he said. "No one has any confidence in the statements they make."
Baltimore Sun reporter Michael Dresser contributed to this article.
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