Hammen said the House members could have even supported a sixth casino, but only if its operators would accept the current tax rate of 67 percent. The owners of National Harbor, the location favored by the leading proponents of a Prince George's site, had stated that with the rate that high, they could not have built the "destination" casino they envisioned. Along with their prospective casino operator, MGM Resorts, National Harbor's owners said such a rate would let them build nothing more than a "slots barn" — a facility they insisted would be out of place in the luxury riverside complex.

According to the analysts' projections, supported by consultants from PricewaterhouseCoopers, none of the existing operators would have lost money if the new casino were accompanied by the right for all casinos to offer table games. But David Cordish, chief executive of the newly opened Maryland Live Casino at Arundel Mills, never accepted those projections and fought the sixth casino all the way, emerging as the big winner in the short term.

Cordish Cos. released a statement saying the casino owner appreciates the "seriousness with which the work group approached its duties."

"Any expansion of gaming facilities in Maryland before the five designated sites are open and performing is premature and not in the best interest of the State," Cordish spokesman Joe Weinberg said. "In fact, no state in the country has added casino sites prior to their initial facilities being open, stabilized, and actual performance data available to analyze."

After the announcement, National Harbor and MGM released statements reaffirming their interest in a Maryland casino.

"MGM Resorts is committed to Maryland and our interest in National Harbor is unabated. With our partners at Peterson Companies, MGM Resorts remains keenly interested in building a world-class destination resort at National Harbor; a project that will bring significant investment, tax revenue, and much-needed jobs to the state," said MGM CEO Jim Murren.

The majority of the work group favored a plan that would have given Rosecroft Raceway and other Prince George's sites the opportunity to compete for the right to open a Prince George's casino with 3,000 slots machines that could not open before July 2016 — an effort to let Arundel Mills and other casinos establish a customer base before facing competition.

The senators and administration appointees proposed a system under which applicants for the Prince George's casino license could receive a slots tax rate as low as 62 percent. They also wanted to give that rate to Cordish and a planned Baltimore site. Under the proposal all of the casinos would have been free to seek further reductions from the proposed Gaming Commission.

The announcement of the failure to reach consensus came as the work group assembled at 4 p.m. for a public meeting that was scheduled at 1 p.m. Much of the Annapolis lobbying corps waited nearby as the members continued to meet behind closed doors in what proved to be a futile effort to resolve their differences.

"It is our recommendation that a special session not be called until a consensus can truly be reached," Morton said.

House Minority Leader Anthony J. O'Donnell, a Calvert County Republican, welcomed the outcome.

"It's evidence of why a special session would be ill-advised to ram something through that is very complicated and may not be in the best interests of the citizens of Maryland," he said.

But Del. Frank Turner, a Howard County Democrat who served on the work group, predicted that the gambling issue will come back.

"Is this going to go away? Never. If we don't do it now, we can do it in the future," he said.

In his Baltimore interview, O'Malley revealed some of his long-standing ambivalence over the issue.

"There are issues that I care about far more than the gaming issue," he said. " I mean, I've never been one that believes that gaming's ever going to replace the important and essential role that individual citizens play when it comes to educating our children, protecting public safety, and protecting our environment."