Mayor Walter E. Washington reiterated yesterday his intention to withhold any city commitment to pay operating subsidies for the Metrorail system until he is satisfied that other regional leaders are seriously considering a regional funding plan to subsidize the complex.

The mayor's remarks came at a hearing before the Senate District Appropriations Subcommittee on a $40.2 million supplemental budget request by the city, which contains no money to pay $350,000 in subsidy costs that pre due July 1.

"I'm more concerned about a regional tax than I am about using this as a lever for a commuter tax" the mayor said later. "But I don't think there's jurisdiction in this area that can sustain the constantly rising costs of rail and bus subsidy.

While the city's share of operating subsidies for this year is relatively small, it is expected to be asked to pay about $13 million to offset rail operating costs in the fiscal year begining Oct. 1. That money has not been requested in the city's proposed 1978 budget.

The mayor's use of the operating subsidy as a lever could jeopardize the opening of 12 additional miles of Metrorail service. This is because suburban Metro board members have indicated that they will put up any money unless the city indicates it also will do so.

Sen. Patrick J. Leahy (D-Vt.), the subcommittee chairman, indicated after the hearing that he might be reluctant to approve giving the city subsidy money, if the ploy doesn't work.

"I'm not going to involve myself in the purely political" maneuvering, Leaphy said. "My only concern is that while the city and suburbs are jockeying for position, we're not able to determine how much to appropriate."

The subcommittee took no action on the city's reauest yesterday, which marked the first session of the subcommittee under its new chairman, Leahy, at which city officials had appeared.

Also at the hearing, the major announced that about 1,700 city students who have applied for loans through the city's guaranteed student loan program could possibly get similar loans from 22 D. C. banks that have agreed to take part in a similar federal program.

The city's program hadeen held up because of an unusually high rate of delinquent payments. However, the Department of Health, Education and Welfare had agreed to immediately make loans available, the mayor said. Students who applied for D. C. loans through the Department of Human Resources will be notified of the newly available loan funds, according to budget director Comer S. Coppie.

In an unrelated area yesterday, the White House announced that President Carter had decided not to act on the City Council's override last month of the major's veto of a bill to strip DHR of control over operations of D. C. General Hospital.

The President's Decision not to act means that the legislation, which sets up an independent commission to run the hospital, will become law if Congress fails to act on it in the next 30 legislative days of Congress.