TWO CONGRESSIONAL panels have now come to opposite about the District's $110-million convention-center plan. In approving the initial $27 million in local borrowing, the House Apropriations Committee has evidently taken the optimistic view that the project is a reasonable gamble that could well generate substantial local tax revenues and spur the redevelopment of the old downtown area near Mount Vernon Square. In contrast, the Senate Appropriations subcommittee has rejected the funds, in the with Chairman Patrick J. Leahy's (D-Vt.) pressimistic view that the center could be an additional drain on a city already burdened with conspicuously high taxes and expenditures.

The House, the full Senate committee and the Senate as a whole still to act on the city's request. In evaluating the project, they should not put too much weight on summary statements about how high public expenditures in the District already are. A Congressional Research Service study just released by Sen. Leahy does conclude that total governmental outlays in the District are higher, per capita, than those in 18 other cities of roughly comparable size. The study also cautions, however, that meaningful comparisons are very hard to make because of problems in allocating various expenditures and great differences among the cities in composition of population, the number of Commuters and other factors affecting public services.

However imprecise such analyses may be, they do underscore the importance of bolstering the District's economy and revenue base - as well as avoiding unwise expenditures. The convention center is, of course, intend to fit this prescription. It does involve gambling on several things: the growths of the national convention business, the District's ability to build, manage and promote such a huge facility efficiently, and private developer's willngness to make substantial investments in that part of town. None of this can be guaranteed to work out absolutely right. On the other hand, a lot of major setback would have occur before the project became fear. Even tastrophe that its most fervent opponents fear. Even if the center cost somewhat more money and drew somewhat less business that its supporters predict, it overall economic effect could still be positive.

If Congress turns down the project, the center's opponents will have been an obligation to suggest alternatives for downtown revival and business development. Otherwise they will be open to the charge that they are merely naysaying and frustrating the city's best efforts to improve its economic base.

A tentative or half-hearted endorsement of the center might be even worst. The fastest way to ensure inefficiency and soaring costs would be for Congress to approve the $27 million this year - and turn around next year and demand still more studies and delays. Instead of second-guessing the local initiative that way, the Senate and House should let the city move ahead - and make it clear that they intend to push local officials hard to stay on schedule, keep costs down, get first'class management for the project and otherwise deliver on their promises.