The Maryland suburbs have formally proposed raising base fares on Metro's buses and trains to 75 cents on April 2, echoing a similar call from Northern Virginia governments last month.

The Maryland proposal, detailed at a meeting of the Metro board's budget committee yesterday, appeared to build momentum toward a steep 10-cent fare increase, which advocates say is needed to help reduce the $180 million operating deficit Metro expects this fiscal year.

The District of Columbia government, normally more willing than the suburbs to shoulder subsidies for Metro, did not formally lay out its views. Yesterday, city officials said they are willing to discuss a 75-cent fare, though they retained the right to reject it.

D.C. officials are also looking at a 5-cent charge for bus transfers, which are now free. With the city facing financial strains, some officials feel fares must rise, even if the increase brings further declines in Metro's ridership.

The Maryland counties, meanwhile, are battling Metro's other members over rail mileage fees. D.C. and Virginia members want to raise mileage fees that many rush-hour riders pay and to abolish Metrorail's single fare for off-peak rides, charging instead for distance traveled.

The committee made no decision yesterday, but to meet the timetable for an April increase, the board must agree on a proposed package by Dec. 16.

Following hearings in January, the board would make a final decision, but could decide on lower fares than those used in the hearings, as has often happened in the past. Metro's rules require that fare rises be approved by four of the board's six voting members, with at least one vote in favor from each jurisdiction.

With the 10-cent increase in base bus fares, Maryland has proposed no change in its bus zone rates, retaining the current 60-cent surcharge for crossing the D.C. line at rush hour and the 25-cent surcharge for crossing between Maryland Zones 1 and 2 at rush hour en route to or from D.C. Virginia, meanwhile, would standardize all rush-hour zone fees at 25 cents. The Potomac crossing fee would rise from 65 to 75 cents.

With a few exceptions, rail fares are standard around the area and are set jointly. Members frequently lobby for rates that will keep their own subsidies or their own riders' fares low.

Maryland residents, for instance, generally take longer-than-average rides on Metrorail. Thus, while Maryland supports the base fare increase, it wants no change in the current peak-hour mileage rate of 13 cents per mile after the first three miles. D.C. and Virginia residents, in contrast, make shorter trips on the average and are more concerned over the base fare.

Similarly, D.C. and Virginia are amenable to establishing a mileage fee for off-peak rail rides.