Key Democrats are signing on to a House of Delegates bill that would place a one-year moratorium on slot machines as part of an effort to stymie Gov. Robert L. Ehrlich Jr.'s campaign to legalize such gambling.

The bill would create a commission to study gambling and would prohibit the General Assembly from legalizing slots for at least a year. Although organizers acknowledged that the bill would have little chance of passage, they called it a rallying point for lawmakers who are uneasy with Ehrlich's proposal to bring thousands upon thousands of slot machines to Maryland.

"I hope that it will slow down the momentum that threatens to push the legislature into enacting an unwise slots proposal," said Del. Peter Franchot (D-Montgomery), who said he has lined up 40 co-sponsors. "I'm not sure it needs to pass in order to accomplish its purpose."

The moratorium bill has the support of many House leaders, including House Majority Leader Kumar P. Barve (D-Montgomery) and three committee chairmen. House Speaker Michael E. Busch (D-Anne Arundel) is also an ardent foe of slots but has not signed on to the bill.

Meanwhile, Ehrlich (R) said yesterday that his slots plan would reserve a chunk of the expected windfall for minority contractors and local governments, but he did not disclose details.

Del. Obie Patterson (D-Prince George's), chairman of the Maryland Legislative Black Caucus, said many black lawmakers want to hear more from Ehrlich on how slots would benefit minorities and communities near racetracks. Two tracks -- Pimlico in Baltimore and Rosecroft Raceway in Prince George's County -- are in mostly black neighborhoods.

"We have to have more specifics," said Patterson, who lives a few blocks from Rosecroft. "I just don't know what his definition means in terms of dollars."

Last fall, Ehrlich campaigned on a platform to allow a total of 10,000 slot machines at four of the state's horse-racing tracks, a proposal that he said could eventually generate $800 million a year in profits for the state.

Since then, he and his aides have considered increasing the number of machines to 16,000 but have not settled on a figure. A spokeswoman said Ehrlich expects to deliver his slots bill next week.

Supporters of the moratorium said the legislature needs more time to ponder the financial and social effects of gambling. They said proposals floated by Ehrlich and the horse-racing industry to allow as many as 4,500 slot machines at a single track would in effect bring enormous casino operations to Maryland.

"I don't have a moral opposition to slots or even a philosophical opposition to slots," said Del. Anthony G. Brown (D-Prince George's), vice chairman of the House Judiciary Committee. "But we're already two or three weeks into the session, and the governor's office has yet to detail their plan for slots -- how many they want, or where they are going to be."

Ehrlich is counting heavily on slots to balance the state's books. His proposed budget for the next fiscal year includes nearly $400 million in revenue from slots, a figure that balloons to $600 million the following year.

Anti-gambling lawmakers have not said how they would make up the difference without slots, though they are talking about a mix of spending cuts and tax increases.

Shareese N. DeLeaver, a spokeswoman for Ehrlich, dismissed the moratorium as a stunt that would only worsen the state's fiscal problems. "It seems like an exercise in futility to derail a bill that hasn't even been proposed yet," she said.

Although the moratorium bill has the backing of much of the House's Democratic leadership, there are some notable exceptions, including Appropriations Committee Chairman Howard P. Rawlings (D-Baltimore), who has introduced a bill that would legalize slots.

Also withholding her support: Ways and Means Committee Chairman Sheila Ellis Hixson (D-Montgomery), whose panel will handle slots legislation.