New Agenda for Reagan . . .

The Tower Commission report hit the White House with hurricane force, and the debris is deep. The commission’s judgment that the Iran- contra scandal was not the system’s fault but that of President Reagan’s nonchalant approach to affairs of state represents a personal and brutally public failure for the President. It must not, and need not, become a national failure for Americans who twice sent him to the White House, reassured by his confident smile.

The first act of clearing away the debris came swiftly, with the replacement of Donald T. Regan as chief of staff and the appointment of Howard H. Baker Jr., former Senate majority leader. The next step is finding a mix of policy ventures that will not leave the damaged President and the nation drifting through the nearly two years left of his term.

The new agenda must acknowledge that there is only the slightest chance that the President will change his ways--will, as even close friends have counseled, snap out of it and take control. Nor can the White House staff pull him through with staged media events that would follow Willie Loman’s axiom that the most important thing is making a good impression.

The policy question that looms over all others for the President, the nation and the world is how to reduce the danger that the competition between the United States and the Soviet Union for world leadership will branch off into war--nuclear or otherwise. The Soviets are losing the peaceful competition--witness the struggle of General Secretary Mikhail S. Gorbachev to shake life into his giant bureaucracy.

The President’s breakdown in leadership came over something so far-fetched--establishing better relations with Iran, a nation committed to terrorism--that even success would hardly have mattered. If Reagan concentrates, as even political opponents say that he can do when he wants to, he can take the lead in producing something that every thinking person on Earth yearns for--a new arms-control treaty to replace the one that he has already discarded and salvage the one surviving treaty that his defense secretary, Casper W. Weinberger, is so anxious to scuttle.

Even hard-liners in the Administration believe that agreement on a far-reaching arms-control treaty is within his grasp if the President will only reach for it. The basic ingredients for a treaty are in sight on the bargaining table in Geneva: major reductions in the heaviest and most destructive missiles, withdrawal by both sides of the hair-trigger missiles with Europe in their sights, and a treaty that can harness, if not block altogether, the catapulting of the nuclear-arms race into outer space. Domestic policies need to provide a minimal distraction for the embattled White House. Reducing the enormous national debt is crucial, but Congress will have the last word on the budget this year, as it had last year. The same is true for welfare reform and long-term health insurance for the elderly--both of which are already before Congress.

The President can make a fresh start. But the clock is running on arms control, and an agreement will require his undivided attention and personal intervention.