There was a moment when Michael Horowitz looked just like that high-speed executive in the Federal Express commercial, the one who juggles a package and telephone calls from three guys named Dave, dealing in Dallas and Denver.

Horowitz, talking on his multibuttoned phone, spun in his chair and, speaking swiftly, commanded his secretary to "Get me Kleinberg and then get me Steinberg."

Honest.

David Kleinberg and Harold Steinberg hold important jobs in the Office of Management and Budget. So does Michael Horowitz, who as counsel to the director of OMB was the unofficial, final arbiter Monday on who in the federal government would work and who would be sent home during the "appropriations hiatus."

Actually, Horowitz hastened to explain, the ultimate authority really was the Justice Department, which is charged with enforcing the Antideficiency Act. That Ulysses S. Grant-era legislation made it necessary to close agencies when the government ran out of money while the president and Congress argued over less than 3/10ths of 1 percent of the federal budget.

Horowitz, 43, Yale law, three-piece pin stripes, striped oxford shirt, seemed to be handling his tasks enthusiastically, even if he was reluctant to discuss the specifics of the decisions he had been making. During the day, he said, he talked with the general counsels of most of the departments, fielded questions from congressional offices and tried to round up information for his boss, budget director David A. Stockman, and other officials.

"If there is an impasse," Horowitz said, "we refer it to the Justice Department." There had been only one "impasse" all day, he said, but he would not say where it was.

"This was an agency that said they had been monitoring Congress closely all day, they were sure that a resolution was going to be worked out, so why stop work and send people home? They did not have lifesaving or property-saving responsibilites"--the only reasons federal employes could remain at work, under guidelines put out by Stockman.

"We discussed the matter. All they could do was suspend operations. Nothing else would be lawful. They said they would keep working. So I pulled the deputy asssistant attorney general out of a meeting. I thought it was important that the Justice Department be informed." At that point, Horowitz said, he was out of it.

"Even in that instance," Horowitz said, "the agency was acting in good faith." He said he had been impressed with the cooperativeness of most federal agencies and that, in fact, the agencies themselves had carried the burden of deciding who was to stay at work and who was to be sent home.

"The problem," he said, "is that there is a potential violation of the Antideficiency Act if you go either way: if you spend too much time shutting down, if there's a lot of Mickey Mouse and bridge playing, you're in violation. If you keep doing business, you also have a violation. So people want to talk about it."

A major concern, he said, was in determining how long it should take an agency to shut down. "I think the president set a strong example there," he said. "Half the White House staff was furloughed at noon . . . . "

The interview was often interrupted, not only by phone calls but also by secretaries and other OMB officials who were besieged with questions: Will furloughed employes be paid? Will the Defense Department furlough anybody? Has enough money been sent to the states to cover the food-stamp program --which is federally financed but operated by the states--during the hiatus?

Horowitz came by his job, he said, after he wrote an article that appeared in Commonsense, a journal of the Republican National Committee. The article, entitled "Why I am a Republican," attracted Stockman's attention and he eventually offered Horowitz the job as his agency's top legal officer.

Where is it written, Horowitz was asked, that the counsel to the director of OMB has almost final authority on who works and who doesn't? Nowhere, Horowitz said in effect. "This is a very informal place. I would hope that we haven't gotten so entrenched in regulation that we" have to spell out that kind of detail.

After all, Horowitz reiterated several times, OMB is the "nerve center" of the federal government. About 200 of its 595 employes were sent home, but the heart of the agency, its budget examiners, stayed on to monitor the programs they know so well.

The phone calls and the energy levels in Horowitz's office began to wind down about 3 Monday afternoon, however, after the House passed the new resolution that ultimately brought an end to the confrontation. It could happen again, of course, Dec. 15. "Nobody wants to go through that again," Horowitz said yesterday, "but if there is a next time, this will have helped.

"We had a problem from the start this time," he said. "If we were to hold contingency planning meetings we would have been charged with sending some kind of confrontational signal . . . " Over the next three or four days, he said, OMB will be conducting a review to determine what went right, what went wrong and what needs changing.

The toughest decision he said he had to make Monday was choosing which of his staff attorneys to send home. He kept two--one an expert on the budget, the other experienced in closing federal agencies (temporarily)--and sent five home..

"I would say, honest to God," Horowitz said, "that there have been no politics on this one."

Long pause.

"At least in terms of the shutdown exercise."