Maryland Gov. Martin O'Malley (Patrick Semansky/AP)

The bill is expected to authorize a Prince George’s County casino and Las Vegas-style table games at Maryland’s five existing slots sites.

“We know where people are, and we know who’s prepared to vote for it today, and we know there are people open to more discussion,” O’Malley said in a brief interview.

The governor said he expects to start circulating the language of the legislation “shortly.” His office is still refining the bill based on input from legislative leaders, O’Malley said.

Among the more touchy issues is how and how much to adjust tax rates for other casino operators to compensate them for the additional competition that would come with a Prince George’s facility, most likely at National Harbor.

O’Malley said his office has used as a starting point recommendations made by a work group he convened this month. Under the group’s plan, casinos in Anne Arundel County and Baltimore would be guaranteed a relatively modest tax break with the possibility of appealing for more assistance later.

O’Malley would not say how his special-session proposal might differ, but he said that it is important to provide casinos some financial certainty going forward, particularly the one in Baltimore, which will be seeking financing for construction in coming months.

O’Malley declined to say much about proposals distributed Tuesday by Cordish Cos., the owner of the Anne Arundel casino, that call for steeper tax relief than envisioned by O’Malley’s work group. But he acknowledged that not everyone will be entirely happy with the bill that emerges from his office.

“I’ve never seen a bill like that on any issue,” O’Malley said.

Any tax relief is not expected to be granted until a Prince George’s casino comes on line, probably several years from now. O’Malley also stressed the importance of allowing Prince George’s voters to have a say on whether the county hosts a casino.

Under current law, gambling expansions require approval by statewide voters after legislative approval. O’Malley has said the vote tally from Prince George’s would also be used to determine whether to move forward with a project there.