The developers of Maryland Live!, a casino scheduled to open next week in Anne Arundel County, said they would lose about 40 percent of their gambling revenue if the state allows a new one to be built in Prince George’s County and warned that they or their competitors could be forced out of business.

“These facilities are not Starbucks that can be put on every street corner and be sustainable,” Joe Weinberg, managing partner of Cordish Cos., told a panel established by Gov. Martin O’Malley (D) to study the effects of expanded gambling. “There’s no way this market can sustain this number of slots.”

But boosters of a plan to build a high-end casino at National Harbor in Prince George’s County countered by saying all casino owners stood to gain financially under an expanded gambling plan that fell short in the legislature in April.

Under that plan, which is getting a fresh look from the work group, the state would also authorize Las Vegas-style table games, such as blackjack and roulette, giving casinos a new source of revenue, and it would bump up the share of slots proceeds the facilities may keep.

The sharply divergent testimony underscored the challenge the work group faces in developing a consensus over that or some other plan in the coming weeks. If it can do so, O’Malley has said he will call a special legislative session in July, with the hope of putting the issue of gambling behind him for the remainder of his tenure.

What is being considered is the largest potential expansion of Maryland’s program since voters authorized five slots locations in 2008. The first meeting of the work group Friday drew some top officials from gambling companies and developers, all of whom have millions of dollars at stake.

Gary Loveman, chairman of Caesars Entertainment, said his company is comfortable with the “new bargain” that was in the bill that died on the final day of the General Assembly’s 90-day session.

Caesars is the sole bidder for a downtown Baltimore casino, and Loveman said that the legalization of table games and a lower tax rate on slots would allow his company to build a better facility.

“It’s a deal we like,” Loveman said, adding that Caesars would also be happy with an alternate plan to allow table games at existing facilities but no additional site in Prince George’s.

The most spirited testimony was delivered by Cordish officials, who plan to open their $550  million casino Wednesday night in neighboring Anne Arundel County.

“We took a chance,” said David Cordish, the company’s chairman. “We put up our money, and you ought to let us open. . . . You don’t expect your own state to make up a new set of rules before you’re already open.”

Cordish argued that the market for his company’s casino at Arundel Mills mall reaches into the District and Northern Virginia — territory to which a Prince George’s casino would also appeal.

Had the company known a Prince George’s casino was under consideration, it would have built a smaller facility, Cordish said. The plan now calls for 4,750 slot machines, making it among the largest in the country.

Milton V. Peterson, the developer of National Harbor, the 300-acre, mixed-use development on the banks of the Potomac River, argued that few Washington tourists would drive to gamble at Arundel Mills. His team pitched a $750 million casino project that would include a hotel, nightclub, spa and other amenities.

Representatives from Penn National Gaming also testified Friday, offering an alternative and more modest plan for a casino at Rosecroft Raceway in Prince George’s County.