Top legislators expressed growing doubts yesterday that they could count on gambling revenue from Gov. Robert L. Ehrlich Jr.'s plan for slot machines at racetracks to close next year's budget gap.

The chairmen of the General Assembly's budget committees - both supporters of slots - said they will prepare budget bills based on the assumption that the $395 million in slots money the governor projected in his budget won't be there.

"This proposal looks like it needs work," said Sen. Ulysses Currie, chairman of the Budget and Taxation Committee.

Meanwhile, the governor's plan was coming under attack for devoting a relatively small portion of the proceeds - 3 percent - to the local jurisdictions that are home to the tracks. That is less than half the share provided in a bill introduced by Del. Howard P. Rawlings, chairman of the House Appropriations Committee.

Mayor Martin O'Malley, who said he had seen only a synopsis of the plan, said it doesn't appear to provide Baltimore with enough money to offset the costs that would come with a large slots operation at Pimlico.

"His bill on its face appears not to calculate the true impact of gambling on the city in terms of additional public safety costs and the damage that gambling addiction can do," O'Malley said.

Moves by the Assembly to draft budget plans that don't rely on slots to balance the budget could cost Ehrlich important leverage.

The governor's strategy to win approval of slots this year depends heavily on concerns that the money is needed to help close a revenue shortfall of about $1.2 billion next year. But yesterday, several lawmakers said they weren't convinced that the bill would bring in the projected revenues even if it passes.

Those reservations, and other concerns about the Ehrlich legislation, could bolster the position of House Speaker Michael E. Busch, who contends that there is no urgency to pass slots legislation this year.

But Ehrlich said last night that he is confident that "the numbers work" in his proposal. He said the slots revenue will still be needed, because "I'm not signing any tax bills."

The governor's legislation, first outlined Thursday, calls for installing 3,000 slot machines each at Pimlico, Laurel and Rosecroft racetracks. Another 1,500 at a track planned for Allegany County would bring the statewide total to 10,500.

Currie, a Prince George's County Democrat, expressed reservations about the governor's proposal after his committee received a briefing yesterday from leaders of the team that drafted the Ehrlich bill, the text of which was still unavailable last night.

Panel members peppered Ehrlich aides Joseph M. Getty and Kenneth H. Masters with questions about whether they could count on the governor's projections of slots revenue.

Sen. Patrick J. Hogan, a Montgomery County Democrat, questioned whether the centralized computer system needed to run the slots operation would be up and running as quickly as the government assumes.

Getty told the panel that Maryland would not need the 18 months it took Delaware to install slots at its tracks because that state was breaking new ground. "We won't have to reinvent the wheel," he said.

Sen. Edward J. Kasemeyer, noting industry analysts' assertions that the plan might not be economically viable for the racetracks, asked whether the administration could count on the tracks to pay the $350 million in fees Ehrlich has built into next year's budget. "Is there a Plan B?" asked Kasemeyer, a Howard County Democrat.

"We anticipated that slots would pass," said Budget Secretary James C. "Chip" DiPaula.

Rawlings said Ehrlich's plan to claim 64 percent of profits for the state could cause problems. "Where it is now, you create the possibility of a New York state situation," he said. In New York, the legislature passed a bill giving the state such a high cut of slots revenue that few racetracks have sought licenses.

Rawlings, a Baltimore Democrat, said his panel, like Currie's, would make provisional budget cuts in case the fees don't materialize. "If we do not pass a slots bill this year, that is going to have an extraordinary impact on the budget," he said.