The day after the collapse of a plan that would allow a Prince George’s County casino, Maryland Gov. Martin O’Malley on Thursday left the door open to calling a special session next month on expanded gambling but lashed out at a handful of legislators for derailing the proposal.

In a statement, O’Malley (D) took aim at three dissenting members of a work group he set up, suggesting they might be acting to provide a casino that opened this month in neighboring Anne Arundel County with “a virtual monopoly for as long as possible.”

Five O’Malley appointees and three state senators on the panel endorsed a plan Wednesday to add a Prince George’s casino, probably at National Harbor, and to allow Las Vegas-style table games at Maryland’s five previously authorized slots locations.

But the dissent of the three other members — all from the House of Delegates — was enough to sink the plan, on which O’Malley was seeking a “consensus.”

House Speaker Michael E. Busch (D-Anne Arundel), who appointed and advised the delegates on the panel, came under fire Thursday not only from O’Malley but also from Prince George’s County Executive Rushern L. Baker III (D), a major casino booster.

One of the 3,200 slot machines at work on the opening night at Maryland Live! Casino in Hanover, Md. (Mark Gail/THE WASHINGTON POST)

Baker said he believed that he had been misled and “lied to” by Busch, a longtime mentor, about the conditions under which House members would support a Prince George’s casino, which MGM Resorts International has been enlisted to operate.

“Was I mad yesterday? Yes, because I felt like I had been lied to,” Baker said in an interview. “I was lied to by Busch.”

Busch said he thought he had been “candid and straightforward with everybody” who had talked to him about gambling in recent weeks. “I have the utmost respect for Rushern Baker. He’s a quality guy and individual,” Busch said.

Busch said House members were willing to agree to a Prince George’s site, but only if the existing 67 percent tax rate for casino owners stayed in place. The rest of the work group endorsed a plan that would lower tax rates to reflect the increased competition.

Under that plan, two casinos — in Anne Arundel and Baltimore — would get at least a 5 percentage point reduction in their tax rates. And the operator of the Prince George’s casino could seek a similar reduction when bidding for a license.

Senate Majority Leader Robert J. Garagiola (D-Montgomery), a member of the work group, said the adjustments were needed, given the introduction of another large-scale casino into Maryland’s market.

“I don’t think anyone could say with a straight face that you could have an effective gaming program if you don’t modify what the operators receive,” Garagiola said. “It just wouldn’t be economically viable.”

That sentiment was echoed by Matthew Gallagher, O’Malley’s chief of staff, in an interview.

Garagiola stressed that even with the tax rate reductions, the state would net more than $200 million in additional money each year from the work group’s plan.

Both Busch and Garagiola expressed a willingness to continue talking about their differences in coming days.

“In fairness to the governor and to the other members of the General Assembly, you have to leave that door open,” Busch said. “I think everybody understood from the outset that a special session would be a challenge.”

Busch’s counterpart, Senate President Thomas V. Mike Miller (D-Calvert), a leading gambling proponent in the legislature, declined again Thursday to discuss the situation with reporters, deferring to Garagiola.

“I’m sure the Senate president is open to entertaining further discussion on this if it can be productive,” Garagiola said. “I don’t want to be spinning our wheels, though.”

Any major gambling expansion in Maryland would have to be ratified by voters statewide following legislative approval.

Advocates for some gaming companies were floating the idea Thursday that lawmakers could pass a scaled-down bill during a special session that would authorize a November ballot measure but leave most details — including tax rates — to be worked out next year.

“The door may be open a crack to that,” Garagiola said. “The challenge with it is the uncertainty that creates.”

In recent weeks, Baker said, he had been given assurances by “the speaker and his folks that they could live with the higher rate structure” that would have allowed the casino owner to keep more of the proceeds and pay less to the state.

But in the end, that proved to be a substantial barrier for the dissenting members of the work group.

Baker said that he and Baltimore Mayor Stephanie Rawlings-Blake (D) thought they had secured a commitment from Busch about what they needed to do to win support for a special session, which had been preliminarily scheduled to begin July 9.

Busch and other opponents were looking for some concrete, independent data that would show an expansion of gaming would benefit the state, create jobs and not hurt other gaming sites, Baker said.

“It caught everyone off guard that House members were going to come back and say, ‘We don’t want to see the rate structure change,’ ” Baker said.

He attributed that decision to pressure from the owners of Maryland Live!, the casino in Anne Arundel County, who have mounted an aggressive lobbying campaign against a Prince George’s casino.