A provision in a Maryland bill that would give Prince George’s County voters an effective veto over hosting a slots casino violates the Maryland Constitution, a state lawyer has concluded.

The development could complicate an already controversial push to expand Maryland’s fledgling gambling program during the 90-day session of the General Assembly.

A bill introduced last week by Sen. Douglas J.J. Peters (D-Prince George’s) seeks voter approval to allow Las Vegas-style table games at Maryland’s five previously authorized slots venues and to add a sixth casino in western Prince George’s County.

Under existing law, gambling expansions in Maryland are subject to a statewide vote. Peters’s bill also would require that for a project to move forward, a majority of Prince George’s voters would have to support the statewide referendum.

An advisory opinion issued Friday by the Maryland attorney general’s office said that making the state’s decision to open a casino contingent on a local vote was “constitutionally impermissible.”

Peters said in an interview Saturday that he considers the development “not fatal” and that he had already spoken with Attorney General Douglas F. Gansler (D) about other ways to ensure county voters get a say in the matter.

“I’m going to explore all the options with the attorney general,” Peters said.

Peters also noted that the Prince George’s County Council could still block construction of a casino through its local zoning power — a move that could be informed by local referendum results.

Gambling opponents suggested the advisory opinion was a more significant setback for the legislation, which is scheduled for a Senate hearing next week.

Gerron Levi, a former member of the House of Delegates who is helping lead the opposition to slots in Prince George’s, said the opinion will make it more difficult for those who don’t want to bring a casino to the county.

“This says there is no local vote that can override a statewide vote,” said Levi, who ran unsuccessfully for county executive in 2010. “As I suspected all along, Prince George’s will not get to decide its own fate. The other 23 jurisdictions of the state will decide for us. We are voiceless in the decision.”

Del. Aisha N. Braveboy (D-Prince George’s), who requested the opinion from the attorney general’s office, said she was not surprised by it and said she thinks that the bill can be reworked.

“In the end, if you have a statewide referendum, you cannot give more power to any one jurisdiction over any other,” she said.

Braveboy, who has opposed slots in the past, said she is keeping an open mind this year, as Prince George’s County Executive Rushern L. Baker III (D) has asked the delegation to do.

Baker is facing mounting pressure to take a firm stand on the bill. A spokesman declined Saturday to comment on the legal opinion.