One of the slot machines at work on the opening night at Maryland Live ! casino in Anne Arundel County. (Photo by Mark Gail/The Washington Post)

O’Malley also met with the two presiding officers of the General Assembly, as a deadline neared to determine whether there is consensus to move forward with a special legislative session.

Under a plan discussed by the O’Malley-launched work group, the two casinos that stand to lose the most market share to a Prince George’s facility — in Baltimore and Anne Arundel County — would see an automatic, 5 percentage-point bump in the slots proceeds they may keep.

Those venues — and the three others previously authorized by the state — could then appeal to a newly created state gaming commission for additional increases. Depending on the size of the requested increase, a final decision could be reserved for the General Assembly.

The tax rate for the new Prince George’s casino would be set through a bidding process, with the same opportunity for adjustments by the gaming commission and legislature.

The state would also authorize Las Vegas-style table games at all six casinos, allowing operators to keep at least 80 percent of the proceeds.

And the state would also transfer responsibility for procurement of slot machines from the state to the casino owners, compensating the owners for their additional cost. The exact amount is not yet determined.

Members of the 11-member work group who described their deliberations cautioned that much remains fluid and numbers are likely to change in coming days. The work group members requested anonymity to speak more freely because they were cautioned against talking to the media.

Monday’s burst of activity came two days before a final scheduled meeting of the work group, at which it is expected to either announce consensus or abandon its efforts. O’Malley has said he will call a special session the week of July 9 if consensus exists on a plan.

During this year’s 90-day session of the legislature, a similar gambling-expansion plan passed the Senate but died in the House of Delegates. O’Malley convened the work group — which consists of administration officials and legislators — to take one more look at the idea.

Under existing law, any gambling expansion passed by the legislature would also require statewide voter approval.

The most likely sites for a Prince George’s casino are National Harbor and Rosecroft Raceway.

House Speaker Michael E. Busch (D-Anne Arundel), who declined to discuss the specific of the work-group deliberations, said the key issue is how to compensate casinos that lose revenue because of a Prince George’s site. “How do you mitigate that loss?” Busch said. “How do you make that fair?”

Busch met earlier in the day with O’Malley and Senate President Thomas V. Mike Miller Jr. (D-Calvert). Aides to all three men described the meeting as cordial.

On Monday afternoon, Senate Minority Leader E.J. Pipkin (R-Cecil) blasted the work group for meeting behind closed doors. Pipkin acknowledged that the group was not under a legal obligation to open its meeting to the public, but he said: “If this isn’t a sad example of the proverbial smoky back room, I don’t know what is.”

The work group is scheduled to meet publicly on Wednesday at 1 p.m. Members said they plan to meet privately that morning.