Hours after Ronald Reagan was shot, even before the bullet was removed from his chest, the White House senior staff was drafting the blueprint for sustaining the momentum of the Reagan administration while the president recovers from his wound.

Presidential counselor Edwin Meese III summarized the strategy yesterday in a single sentence:

"Basically, the message is that this government is doing business as usual."

Until the president is safely returned to the White House and fully back at work in the Oval Office, every public gesture and activity will be aimed at demonstrating that nothing fundamental has changed while he is away. As it happens, the Reagan White House had at its fingertips a handy guide from history -- how the Eisenhower administration maintained its equilibrium when Ike was hospitalized with a heart attack on Sept. 24, 1955.

"It's just as if the president were here in the Oval Office the way the White House is running," said Michael K. Deaver, the White House deputy chief of staff who was at the president's side when he was wounded Monday.

Deaver's comment reflects a confidence among senior advisers that Reagan, from his hospital bed, will be able to make the decisions that are required of a president.

The White House approach also demonstrated that Meese, Deaver and chief of staff James A. Baker III have a public relations awareness of the need to show that the government has not been thrown off stride, despite the trauma of the attack.

Yesterday, for instance, the president's three senior advisers held their usual early-morning meeting -- only this time it was around the president's hospital bed. At breakfast, the president signed a bill, using his hosptial tray as a desk. Later, Vice President Bush presided at an informal Cabinet meeting, subbed for Reagan at a meeting with congressional leaders and lunched with the Dutch prime minister.

These small but important gestures of continuity could well have been lifted from the days of 1955 when Vice President Richard Nixon filled in for the recuperating president while Eisenhower's senior staff kept the government running.

Late Monday afternoon, when the extent of Reagan's injury was not fully known, White House speechwriter Tony Dolan sent Robert M. Garrick, Meese's dupty, a memorandum. It began this way. "During the Eisenhower heart attack period, the administration kept to the theme of business as usuall."

Dolan's memo summarized the approach of the White House staff after President Eisenhower's heart attack.

"1. Officials noted in their public statements that President Eisenhower had established a Cabinet style government -- 'the Ike team' -- and had carefully delegated authority [which] had prepared the government for just such an eventuality.

"2. The administration kept to previously announced schedules of government activities, even to trips abroad by Cabinet officers.

"3. The first Cabinet meeting after Ike's attack was opened with prayers for his recovery.

"4. Then-Vice President Nixon noted the incredibly heightened sensitivity of the press during this period. Even a wrong expression in a still photo could be widely misinterpreted. It was a time for carefully guarded words and actions, especially for the vice president. It was important, Nixon noted, to appear neither brash nor timid."

This memo could well have described the way that the senior White House staff -- and the vice president -- behaved on the second day of Reagan's hospitalization.

After a breakfast meeting at the hospital, the White House "Big Three" adjourned for their regular morning meeting with Reagan. This meeting was held in the barren intensive-care unit with the three staff members grouped around the bed.

"I've really screwed the schedule," Reagan said to Deaver, who keeps the president's schedule in the White House.

In fact, every effort was made yesterday -- as it will be the rest of the week -- to see that the Reagan schedule is carried out by Bush. It is what will happen again today, when Bush presides over a National Security Council meeting, and again on Thursday when the vice president is scheduled to chair a full meeting of the Cabinet.

In all these actions both Bush and the senior staff are careful to weigh their words, in the manner suggested by the Eisenhower staff experience, so that no one forms the impression that Bush has taken over as president.

"The decisions are being made by the president," said Meese, in words virtually identical to those uttered by Baker and Deaver.

In administering the interim government until the president's full recovery, White House aides are counting on the enormous asset of a presidential style that they perceive as gritty and courageous.

The Reagan wisecracks in the hospital bed -- "Does Nancy know about us?" the president joked to a nurse Monday night -- and his physical resilence have convinced his aides that the interim without him will be relatively short. It has to be, in the opinion of his closest congressional ally, Sen. Paul Laxalt (R-Nev.). who thinks that there's no substitute for Reagan when it comes to political salesmanship.

"Sympathy is a short-term commodity on Capital Hill," says Laxalt, explaining why Reagan's presence will be needed to maintain public support for his economic program.

But the Nevadan predicts the White House staff will function smoothly in Reagan's absence and that Bush's performance will be acceptable to all factions. He also believes that the president has the congressional schedule on his side in the form of the Easter recess, which will begin on April 10 and extend to April 27.

"I would hope by that time Reagan would be ready to go to work," Laxalt said.

While no one is making a prediction like this at the White House, the private expectations clearly are very high. Reagan was scheduled to move out of his intensive-care unit to a private room late last night or early today. Aides are talking about another 10 days of hospitalization, and some are even more optimistic than that.

"The doctors are treating him as they would any 50-year-old man," quipped Meese yesterday.

Reagan is 70 years old. He is also, to hear his doctors and his aides talk about it, tougher than the proverbial boot. He was at first unaware that he was shot, and he joked with doctors on the operating table.When a doctor told him it would be two months before he could work at his Santa Barbara ranch, Reagan held up one finger.

The steady reporting of Reagan one-liners and the meetings at Reagan's bed are all calculated, of course, to put the best possible light on the president's condition and to avoid dwelling on the trauma of the gunshot wound.

But Reagan's stylistic respone to the shooting has made the task of his managers easier.

Even opponents of the president have praised his grace under pressure. Even critics of the White House staff acknowledge that it has performed relatively smoothly in the present crisis. Even opponents of Vice President Bush found little on which to fault him yesterday.

Traumatic as the crisis has been, the realities of politics lead those who are in charge of pushing the president's program to ask themselves if there are any short-term benefits that can be derived from the violence that erupted outside the Washington Hilton Hotel on Monday. No one pretends to know the answer to this now. But Reagan and his aides will take any help they can get.

Asked whether the president's program would benefit from what had happened, his top aide Meese replied this way.

"I honestly don't know. But I don't think the president's programs will be hurt."