Maryland lawmakers are poised this week to transform the state's restrictive gambling law into one that allows six full-blown Vegas-style casinos, complete with roulette wheels and poker tables open 24 hours a day.

It's a long way from the legislation that squeaked through the General Assembly five years ago, when the state cracked open the door to gambling. Then, Gov.Martin O'Malleypromised a "limited" program: five slots-only casinos whose sizes would be kept in check by the nation's highest casino tax rate.

The expansion the General Assembly is considering in its special session would mark a significant philosophical shift — one favored by the industry. Rather than slots halls, the legislation envisions big gambling-and-entertainment destinations that stand to attract more customers from across the economic spectrum.

"They really are considering restructuring the whole model," said William R. Eadington, a professor of economics at the University of Nevada and director of the Institute for the Study of Gambling and Commercial Gaming.

Gerron Levi, a formerPrince George's Countydelegate who voted against gambling in 2007, said she believes most lawmakers never intended for the state to move so far so fast.

"The notion that we would move so quickly to full-scale Las Vegas casinos throughout the state was not comprehended, understood or embraced at the time," Levi said.

While opponents tried to argue back in 2007 that Maryland would eventually expand gambling, she said, "the governor and others who sold this said otherwise."

The state's current gambling law already allows for 15,000 slot machines, which are a major part of any casino. When fully operational, the number of slots at the Maryland Live casino at Arundel Mills and the one planned for downtown Baltimore will put them among the nation's 15 largest commercial casinos.

The governor's bill would authorize a new casino inPrince George's County— it, too, would make the top 15 — and an unlimited amount of table games at all six sites. If it is approved by the legislature, voters will have the final say in a referendum this November.

Were all six casinos fully up and running, legislative analysts project the state would have the ninth-highest consumer spending on gambling in the country — in league with Illinois, Missouri and Iowa, respectively home to 10, 12 and 18 casinos.

O'Malley, who said last week he is "so sick" of the issue, says he's pushing the legislation partly to quiet the drumbeat for more gambling so state leaders can move on to address other pressing matters.

He and other gambling supporters, led by Senate PresidentThomas V. Mike Miller, also say they want to make Maryland's casinos competitive with surrounding states' and gain the tax revenue and jobs that can come from expansion.

Boosters of a proposed site at the National Harbor development, on the Potomac River in Prince George's County, say the glitzy casino that MGM Resorts wants to build there would be an especial plus for the state's economy.

The location near Washington offers "this unique opportunity, with the nation's capital, to be a destination facility," said Sen. Richard Madaleno, a Montgomery County Democrat who supports expansion.

Critics of the governor's proposal say that a sixth casino would saturate the market and encourage gambling addiction, all for very little new revenue.

Alan R. Woinski, an analyst who has worked as a gambling industry consultant in other states, said a new casino at National Harbor could be a "scud missile" that blows up the market for existing venues along with the state's projected revenue from casino taxes.

He pointed to a new mega-casino that opened recently in the Chicago area, which he said took business away from eight others in two states.

"Every casino that opens now is a disaster for existing casinos," Woinski said.

But he said Maryland politicians are following a predictable pattern: First, pledging to fund programs with gambling revenues. When the projections fall short — as they have in Maryland — there is a push to do more. "They expand," Woinski said. "They start adding table games."