WHEN 70 PERCENT of the city's residents and potential voters are renters, and when rental housing is dwindling, especially for people with low incomes, rent control becomes a hot issue. And so it is that in Washington this year, with six city council seats up for election, the city's policiticans have said that rent control is too hot to touch. Last week, the council extended the existing and outdated rent control law before the August recess, failing even to revise the program, let alone do away with it. As for the mayor, he has yet to deliver his long-awaited proposal for new rent control legislation. The net effect is stagnation on an issue that is key to the city's future.

Under the current rent control law, this city can expect a continued decline in construction of new apartment buildings and in maintenance of existing ones. The kind of rent control the District has does little to inhibit inflation's effect on the cost of fuel oil, repair work or owning rental property. This act as a disincentive to constructing buildings in Washington; it is especially discouraging to developers interested in building apartments outside the popular and high-rent areas near downtown. Consequently, apartments in distant parts of the city that poor people can afford are not growing in number. The basic fact about rent control in Washington today is that it is encouraging neglect of apartment buildings and discouraging construction of new, low-priced apartments. In other words, rent control is not benefitting the poor.

But for some people, there is no argument strong enough to persuade them that rent control is anything but a blessing. They view any argument against it as the raving of greedy landowners. What they do not see is the increasing number of poor families forced to live together in tenement conditions because of the shortage of affordable apartments; they also don't see the responsible small investors who are getting out of the apartment building business or neglecting their properties because they are losing money.

As a political issue, the argument on rent control has not gone beyond an us (renters) versus them (landlords) level in which the renters demand unconditionally that politicians keep rent control in place. Caught between the reality of rent control's harm to the city's housing stock and the politically potent number of renters, politicians are backing away from the issue as quickly as they can.

But alternative ideas, not caution to the point of paralysis, are what is needed. The best idea may be to eliminate rent control gradually. Currently, new buildings are not covered by rent control. But builders say that, as long as there are controls on the old buildings, the city will be tempted to extend them. The result is not much new apartment construction. The answer to that problem may be to begin a year-by-year plan for raising rent ceilings until all controls are removed. At the same time, either rent subsidies or tax incentives for owners of apartment buildings with moderate rents could help some poor people keep their apartments in popular center-city areas. As a matter of social policy, it is important that poor people not be purged from the city's midst. To give builders incentives to put up apartments is the challenge.