ANNAPOLIS, JAN. 11 -- The proposed trolley linking Bethesda and Silver Spring appears doomed, at least for now, by a sharply higher cost estimate released today and the Montgomery County executive's decision not to fight for it.

Building the 4.4-mile light-rail line would cost as much as $224 million, according to a study by the Maryland Department of Transportation, a jump of more than $90 million.

State and Montgomery County leaders said today that the higher cost puts the trolley out of reach.

"In any case, we're talking about a project that doesn't need to be built now," County Executive Neal Potter said.

However, Potter said a trolley line probably will be needed and built along the corridor within 10 years, as congestion and environmental concerns push more county residents out of their cars.

With the project teetering on the brink, county leaders argued that Montgomery still should receive the $70 million that Gov. William Donald Schaefer set aside for trolley line construction. The money could be used on badly needed road improvements, they said.

"It would be unconscionable to take that money out of the county because we have such serious transportation needs," said County Council member Bruce T. Adams, who supported the trolley if the state would build it.

But state Transportation Secretary James Lighthizer, who briefed Potter on the new cost estimate this week, has other ideas.

"I told him that I'm going to recommend that if they don't use {the money} on light rail, it go back into the transportation fund," Lighthizer said. If returned to the transportation fund, the money could be used anywhere in the state.

Even opponents of the proposed Montgomery County trolley line were shocked by the cost escalation.

"Common sense would indicate this should finish it off," said Anthony Czajkowski, founder of the Bethesda-Chevy Chase coalition that has fought the project.

"But I'm not going to rest easy until -- like the beast this is -- the final spike is driven through the heart," said Czajkowski.

Opponents argue that the trolley would harm Rock Creek Park and disturb densely settled neighborhoods along its route.

In addition, they question ridership estimates, saying that the trolley would not significantly reduce traffic along heavily traveled East West Highway.

Politically, the cards may be stacked against the trolley.

Of the nine members on the recently elected council, five were endorsed by a political action committee established to fight the light-rail project.

Two others also favor construction only if the state pays all construction costs, including overruns.

A county study in 1989 put the cost of construction at $102.8 million, but additions ordered by the County Council -- including a bridge over Connecticut Avenue and a tunnel under the CSX main rail line -- pushed the county's estimate to $132.8 million.

In their new study, state officials projected a rapid rise in inflation as of 1994 -- midpoint in a construction schedule -- and factored in contingency costs that should have been included earlier.

The new study, although finding the project "viable," also said the county underestimated the trolley's annual operating expenses by more than $1 million.

The higher cost estimates are expected to shift the immediate debate back to the plan for a hiker-biker trail along the abandoned CSX freight line, which is owned by the county.

The trail was to be a part of the trolley project, and advocates are expected to push for it.

The council is likely to come under pressure to put the land to an interim recreational use.

In an interview after meeting with the governor today, Potter said he supports installing an inexpensive trail but said it should not foreclose the possibility of building the trolley line.

"We should find a way of doing something economical and pleasant that won't have to be done over later," Potter said.

However, county planners said that putting a hiker-biker trail in now would make it more difficult to add a trolley along the right of way later.