Every weekday evening, hours after the bureaucracy has locked up and gone home, Jim J. Tozzi rides a Metrobus home toward Tysons Corner with part of the federal government's future in his lap.

Sheafs of papers stacked on his knees and piled on the seat next to him receive his full concentration. A preoccupied, somewhat forbidding figure in a pinstriped tailored suit, Tozzi isn't usually bothered by fellow passengers. a

The papers include pleas from lobbyists requesting this or that from the government, but the most important part of the stack is the daily output of federal regulations that have made their way to Tozzi for his thumbs-up, thumbs-down opinion.

Tozzi is deputy administrator for informatgion and regulatory affairs of the Office of Management and Budget, the career official responsible for reviewing every one of the 3,500 regulations issued by the government in a year, after his staff of 30 desk officers have scrutinized them.

Since the presidential election, the OMB's authority over the government's regulatory actions has grown dramatically. Under an executive order issued by President Reagan in February, the OMB is responsible for seeing that executive branch agencies obey his new regulatory relief policy, which calls for the most cost-effective approach to meeting regulatory requirements.

Tozzi and another career deputy OMB administrator, Thomas Hopkins, share that responsibility under James C. Miller, III, the Reagan political appointee who directs regulatory policy.

Tozzi also directs a new OMB program to review all requests to the public for information by the federal government, to limit the paperwork burden on the private sector. After Dec. 31, when the program takes full effect, anyone who receives a federal information from that doesn't have OMB's seal of approval can safely toss it into the wastebasket.

Congress gave the OMB this authority last year in the Paperwork Reduction Act. Tozzi, it turns out, is not only its day-to-day administrator. He also was one of the chief lobbyists who helped get it enacted.

In a city of bureaucrats, Tozzi is considered an original.

His staff has called him the ayatollah, a not-entirely-forgiving reference to his demanding ways. Another nickname last year was Stealth, after Tozzi helped defeat the Defense Department and the National Security Council in the battle over the Paperwork Act, which the intelligence commounity fought, fearing that their computer operations would be restricted. Like a Stealth bomber, Tozzi reached his target while shielding his whereabouts from adversaries, aides say.

A visitor to his office is startled by its emptiness. Not a single piece of paper litters the polished top of the government-issue desk; it is as if Tozzi has banished paperwork from his sight.

He also shuns memos, reports and other written messages in favor of direct conversation. "I don't want to leave fingerprints," Tozzi said with a grin, in a very rare interview.

The real reason,he said, is that memos must be exact, like court documents, and thus are too time-consuming."If there are papers piling up in the job I have now, it means I'm either not delegating authority or I'm not working hard enough." There are no papers piling up, at least on his desk.

But what really puts him into a select group is his skill at accumulating the political currency that keeps him in power when administrations change hands and new presidential appointees take over at the OMB, a power based on pesonal delings, associates say.

"A lot of people in business have respect for his opinion. When he says, 'Yeah, this is important,' they'll listen," said Robert Coakley, an aide to Sen. Lawton Chiles (D-Fla.), who led the Senate fight for the Paperwork Act.

"There are damn few like him," said Richard Patterson, Washington manager for Dow Chemical Co.

Enthusiasm for Tozzi is more restrained among environmental and consumer lobbyists, who recall his tight rein on the Environmental Protection Agency as its chief budget overseer at the OMB in the 1970s. But some, like Alan Morrison, director of the Public Citizen Litigation Group, formed by Ralph Nader, have come away from encounters with Tozzi impressed by his fairness.

Objectivity and restraint are two sources of his political clout and durability, his associates say. Tozzi said his father, born in northern Italy, operated a grocery store in Waynesburg, Ohio. In the many years he worked there, Tozzi said, he never heard his father raise his voice, and he has tried to follow that style. Speak softly and carry the biggest stick you can find, Tozzi says.

Challenging critics of the bureaucracy, Tozzi said a good bureaucrat is as much an entrepreneur as any business executive, except his objective is power. "He has to amass power to get things done," said Tozzi, drawing a distinction between gaining power and using it. "What I spend it on is what the president or the director of OMB wants done.

"Some of my friends say I'm just a hit man for the president," said Tozzi, who at 43 is serving his fifth president. But if a lawyer can serve different clients, why not a bureaucrat? he asks. Hit man? No. Loyal supporter of the office of the presidency? Yes, Tozzi says.

Tozzi's institutional loyalty and his entrepreneurial interests dovetailed in the fight over the Paperwork Act last year. Business groups actively backed it, anticipating that it would lighten government control. President Carter and key advisers wanted it, in part as an election-year achievement, in part as a means of making government work better.

But even with that support, the bill almost died several times. No doctor with a stricken patient worked harder than Tozzi did to resuscitate it, said Harrison Wellford, a top OMB official under Carter.

His most direct role was in persuading the business groups to support passage of the bill after November's election rather than wait for a new version from the Reagan administration.

"Business could have stopped it if they had wanted to," said Coakley, the aide to Chiles. What helped overcome their reservations, he said, was the fact that Tozzi probably would be running the new program.

Beyond that, Tozzi's associates say he played a crucial role as "Stealth" in the parliamentary maneuvering by Chiles and Rep. Jack Brooks (D-Tex.) late last year that saw the Paperwork Act brought up, with almost no advance notice, in both the Senate and House, catching its military opponents off guard. On this subject Tozzi is Delphic. "Maybe I participated. I think you'd better speak to Chiles and Brooks.

But Tozzi admits to some pride of authorship. A framed, signed copy of the Paperwork Reduction Act hangs in his office, one of the few pieces of decoration there.

" cashed in every chit I had for that," he said.