ANNAPOLIS -- Maryland Gov. Martin O'Malley chastised members of the House of Delegates for backing away from a deal to expand gambling in the state at the last minute, which for now has halted plans for a proposed casino at National Harbor.

After coming so close to an agreement that would have authorized a sixth state casino site, in Prince George's County, and table games such as blackjack and roulette, delegates on an O'Malley-created commission voted against a measure to lower the state's 67 percent tax rate on slots.

Del. Peter Hammen, D-Baltimore, said House lawmakers couldn't stomach reducing one of the nation's highest tax rates on gambling.

O'Malley, who earlier this week had expressed confidence that a deal would be struck, offered a scathing assessment of what he called the House leadership's "last-minute" decision to derail a consensus on gambling.

"Finding common ground will be difficult if House leadership has become invested in the notion that the Anne Arundel site should enjoy a virtual monopoly for as long as possible," O'Malley said Thursday evening.

House Speaker Michael Busch, D-Anne Arundel, dismissed the notion that his interests as an Anne Arundel County representative -- home of Maryland Live!, the state's newest casino and the biggest opponent of a casino in Prince George's -- had anything to do with the House's split from the rest of the commission, all of whom voted in favor of lowering the slots tax rate.

"I'm responsible for the Maryland House of Delegates and what's in the best interest of the state of Maryland," he said. "Certainly I like to think I'm supportive of Anne Arundel County, but I'm the speaker."

Busch also defended the work of the commission and the delegates he appointed to it. Agreements were reached on "98 percent" of the gambling issues at stake, he said, and the door is still open for negotiations to be made and a special session to be called.

State analysts estimate the gambling proposals made by the commission would generate an extra $223 million a year for the state's education trust fund.

The legislature has until Aug. 16 to pass referendum legislation that would put the expansion of gambling to a statewide vote on the November ballot.