The owner of Maryland’s largest casino said Monday that an accounting firm has found that nearly half its revenue is coming from the Washington area, a finding with “enormous” implications for the debate over whether to allow a new casino in Prince George’s County.

David S. Cordish, chairman of the Cordish Cos, at the ribbon-cutting for his casino last month.(Mark Gail/The Washington Post)

“The facts as to where Live!’s customers reside are no longer a hypothetical debate,” Cordish wrote in the e-mail, a copy of which was obtained by The Washington Post. “We now have the reality of our database.”

The e-mail was sent on the eve of a key meeting between Gov. Martin O’Malley (D), House Speaker Michael E. Busch (D-Anne Arundel) and Senate President Thomas V. Mike Miller Jr. (D-Calvert).

O’Malley told reporters earlier Monday that he thinks the odds of a special legislative session on expanded gambling are now better than 50 percent. Any plan considered in the session is likely to include a new casino in Prince George’s, most likely at National Harbor.

Cordish said that Ernst & Young had analyzed the home addresses of the 121,958 people who signed up during the first 30 days of the casino’s operation for Live! Reward Cards.

Forty-seven percent of the revenue generated by those customers came from addresses south of Maryland Live! in Prince George’s and Montgomery counties, Virginia and the District, Cordish wrote.

Milton V. Peterson, developer of National Harbor, has said repeatedly that he sees limited overlap in markets between the two sites, and he has accused Cordish of being afraid of competition.

Cordish goes on his e-mail to argue that the negative impact of a Prince George’s facility would be so great to his site and one planned in Baltimore that the state would actually get less tax money than under alternate scenarios. Those include authorizing Las Vegas-style table games only at the state’s five existing slots locations.

If a Prince George’s site is authorized, Maryland Live! would be flanked by other large casinos to its north and south.

“Having three weak facilities, rather than two healthy ones, will result not only in a net loss in revenues to the state, but a net loss in jobs, as all the facilities would have to cut back to survive,” Cordish said. “Your consideration of the above in deciding on the wisdom, or lack thereof, for a special session is sincerely appreciated.”