Today the Senate will start debate on extending rent-controls, which expire March 31. The House has already passed its own rent-ceiling bill. Neither of the measures follow the administration's original plans. The great gap between supply and demand in available housing means that just how far these bills are modified during the next few days will probably affect the national economy as much as any other legislation facing Congress this year.

The original federal rent controls were a wartime measure, but they were drawn up to meet a serious problem that was rooted well back before the war: the fact that American builders cannot afford to put up housing for people who need it. Even in the depression year of 1933, with an estimated 5,000,000 vacant dwelling units, there was a 20 to 30 percent shortage of housing facilities for lower income groups. The causes for this condition continue, most important being the high cost of building materials and capital, ancient and discriminatory building codes, and restrictive measures by unions and contractors. Wartime full employment pushed the shortage up to include middle priced housing, necessitating controls to stop soaring rents.

Now a powerful real-estate lobby in Congress is doing its best to emasculate these controls. The real-estate men are claiming that the ceilings have made building unprofitable and are therefore prolonging the housing shortage, that rent controls are making it impossible for landlords to get a "fair return" on their money.

Both arguments are invalid. There was a serious low-rent housing shortage (and it is in low-rent housing that the present shortage exists) before controls were even considered. The 1933 figures show this. And the present federal controls include "hardship clauses," especially written to let the landlord secure rent-hikes if he can show that his income is seriously falling relative to his costs. More than that, for the last few years real-estate operators have been using leases as a very effective anti-tenant weapon, keeping people paying on an insecure month-to-month basis, unless they agree to rent rises.

The two present bills show some of the influence of this lobby. The House bill extends controls for 15 months, guarantees the ever-mentioned "fair-return," and gives state and city governments local jurisdiction on lifting ceilings completely. The Senate bill is even weaker, providing for an automatic 15 percent jump in rents while it is in effect.

Neither is strong enough for the job. Until builders, or alternatively the Federal government, can come through with housing to shelter people who cannot afford to pay increasd rents--an estimated 600,000 people in New York City alone--strict controls are necessary to keep overwhelming demand from pushing rents high out of reach. The original Federal controls are just good enough for the job; the comparative present stability of rents shows this. If Congress weakens these controls, it will benefit nobody but the men who have so far terribly failed to cure the housing shortage on their own.