WHETHER NERVOUS city politicians like it or not, the pressure is on to build a new prison in the District of Columbia -- and the more pressure the better. Mayor Barry may not consider it an issue worthy of discussion during the campaign, but more and more members of the D.C. Council are recognizing the need to do something besides look the other way every time the issue comes up. Even Chairman David Clarke -- who still opposes building any prison inside the District of Columbia -- wants it understood that he is "prepared to have a decision made whether I win or lose." If the city government is to begin to repair the damage of years of mismanagement and delay, Mr. Clarke should lose this one. But his willingness to move is important, even if the council's judiciary committee, headed by Wilhelmina Rolark, hasn't yet mustered the courage to act with dispatch.

Chairman Clarke still points to council rules that put off consideration of the issue until September at the earliest. That means within days of the primary elections, which spells relief for any politically anxious incumbents up for election. But at this point, their attitudes and records on the prison question are on the books for voters to consider, and the object is to act as quickly as is legally possible. If the council insists that it should have a role in the building of the prison, then get on with it. If this merely provides an excuse for interminable hearings and other stalling tactics, the consequences could touch far more than just the prison issue. The city government's ability to function forthrightly and efficiently on a joint project with the federal government will be under scrutiny. Failure to measure up could be costly.

This isn't a question of the city's jumping through a congressional hoop on command, or bowing and scraping just to preserve its limited home-rule franchise. In this instance the federal government is offering land, money and assistance to accomplish something, and the city's response has been anything but impressive. If the adminstration starts playing games with the project or changing the conditions and, say, stuffing federal prisoners in the new facility instead letting the city have full use of it, then that would be something to resist. But right now, Mayor Barry, Mr. Clarke and Mrs. Rolark have a serious responsibility to make something happen -- fast.