Mounting congressional pressure and public displeasure with gasoline lines in the Washington area led to yesterday's decision by the Maryland and Virginia governors and the District mayor to meet Monday to forge a unified plan of attack.

On Capitol Hill yesterday, six members of Congress from the metropolitan area met with a top U.S. energy official to ask why the national gasoline shortage has reached such proportions here.

What emerged was a general sense that the crisis can be ended and an arrangement for a gasolinee summit meeting Monday of Maryland Gov. Harry Hughes, Virginia Gov. John Dalton and District Mayor Marion Barry to agree on a "comprehensive and uniform" plan of attack.

All three leaders have independently ordered minimum purchase requirements to end "topping off" of gas tanks and staggered service station hours so that motorists can hope to find gasoline at any hour of the day.

But it took an initiative by Rep. Herbert E. Harris (D-Va.), a strong advocate of odd-even rationing and the chairman of yesterday's Capitol Hilll meeting, to force the two governors and the mayor to actually sit down together to forge a regional plan of action.

"I hope Monday's meeting will lead to a comprehensive plan that will be implemented immediately that would include odd-even sales, minimum purchases and staggered hours," said Harris. "What we're really anxious to do is restore public confidence."

Odd-even sales, a plan that allows motorists with odd-numbered license plates to buy gas on odd-numbered days of the month and those with even numbers to buy on even-numbered days, has been credited by federal officials with helping to end chaotic gas lines in many California cities.

But Hughes, Dalton and Barry have been skittish about it so far. In a press conference yesterday, Barry called it "a drastic measure . . . If I took that measure now, we would have no other options." However, he added that he would impose an odd-even plan if the minimum purchase requirement wasn't working.

In yesterday's Capitol Hill meeting, David Barin, head of the powerful regulatory arm of the U.S. Department of Energy, told Harris and the other local members of Congress that gas lines in California ended "overnight" after strong measures like odd-even sales were imposed and after motorists calmed down and resigned themselves to driving less.

Bardin said a DOE analysis of gasoline deliveries to the Washington area shows that the supply shortfall here is no greater than anywhere else in the country.

"You can run into this line situation anywhere in the country, particularly in metropolitan areas, if you have a pile-up of demand," Bardin said.

He said such a pile-up can be caused by a sudden loss of public confidence that sends people rushing to gas-stations, or by a weekend of nice weather that makes everyone want to get out of town at once.

The pipeline system that supplies gasoline to the washington areas simply cannot meet such a sudden surge in demand, particularly when suppliers are short anyway, according to Bardin.

He said that the public here must learn - as people in California have - to overcome the "automatic instinct that gets you in the gut to keep your tank full."

"People simply have to use their cars less . . . use Metro, carpooling, fargo trips," said Bardin. He said people need self-discipline, patience and a sense of humor to bring an end to the lines.

If the general sense of panic can be brought under control, Bardin said that the Washington area will be close to normal with a tight gasoline supply situation but without the inconvenience of gas lines.

U.S. Energy Secretary James R Schlesinger, Bardin's boss, said on Thursday that an unexpected spurt in U.S. oil imports may make it easier for motorists to buy gasoline this summer. "Gas lines should end around the country," Schlesinger said.

But bardin said yesterday that this "slight not be a significantly greater quantity.

The important point is it's not going to get significantly worse," said Bardin. "It's going to be about the same (in the near future)."

From a psychological point of view, he said, this means that motorists need not line up for gas because an adequate - if somewhat short - quantity will be available the next day or week when they need it.

Bardin characterized the shortage as "on the order of 10 percent" and this went unchallenged except for an observation by Rep. Joseph L. Fisher (D-Va.) that in Virginia the shortage at service stations seems to be about 20 percent.

In fact, the shortage at the pumps where the average motorist buys gas is now in the range of 20 to 25 percent in the Washington area, according to oil company figures on what they are supplying to service stations.

What Bardin failed to explain to the members of Congress is that prority users like farmers and special state emergency supplies soak up a good deal of the national gasoline supply before it reaches the service stations.

By the time it does reach the stations, the 10 percent national and Washington area gasoline shortage has become that 20 to 25 percent shortage for the averagemotorist.