ONE OF MARION BARRY'S boldest campaign promises last year was a pledge to double the number of summer jobs for young people. That is a risky promise because it raises hopes that can be disappointed if the city doesn't deliver. And this is a danger today, with public schools setto close in less than three weeks: City officials claim that only halfof 30,000 promised jobs have materialized, while more than 31,000 youngpeople have applied for work.

The most important part of Mayor Barry'sproposals depend on the federal government. It is a budget request formoney to provide 9,000 jobs. This request has been before the White House Office of Management and Budget; now it is up to Congress to act quickly, and the sooner a House subcommittee headed by Rep. Charles Wilson (D-Tex.) responds, the faster this request can go through Congress and on to President Carter. Even some informal indication of a decision by Congress would allow the local government to proceed. The city also expects to get 2,000 jobs from federal agencies and departments. But job interviews have only begun. Here again, a sense of urgency is needed.

What about city hall itself, which is responsible for processing job offers from the local business community? Matthew F. Shannon, acting director of the D.C. Department of Labor, has been critical of the efforts of the Metropolitan Washington Board of Trade and the National Alliance of Business. He claims that fewer than 600 of the jobs could be filled by young people and cites the difficulty of placing applicants who are 14 and 15 years old.

Yet the private effort has never pretended to provide jobs for children under 16. What it has done is identify and refer to city officials some 2,800 job offers so far and - according to officials - the District has fallen about 1,200 jobs behind in acting on these offers. With such delays between offers and the arrivals of any applicants, obviously some employers either hire from elsewhere or withdraw their offers. In addition, the private effort claims some other impressive statistics: roughly 1,600 young people rehired from last year and 6,300 whose part-time jobs have been made full-time for the summer.

Rather than finding fault with the private effort, the city should pull out all stops to fill every job as fast as it is offered - while continuing to impress upon Congress the importance of the budget request. Mayor Barry's promise may be a tall order, but now that it has been made, it demands an urgent response downtown as well as on Capitol Hill.