Vice President George Bush stretched back in his office chair, at ease as he reflected on the power and the problems awaiting him when the V word is erased from his title and "I'm president, I'm the one who's calling the shots."

With exhilaration tempered by "this deficit looming over everything," Bush takes office at noon Friday, convinced there is neither a need nor a mandate for dramatic change to put his imprint on the White House."Automatically, that happens," he said, with the transfer of power from Ronald Reagan's 40th presidency to his 41st.

As keynotes to the Bush era, the past eight years are likely to weigh far more heavily than the first hundred days.

"I've been a part of this administration, and it isn't like there is a need for radical change," the president-elect said in an interview in his vice presidential office, across a narrow, private street from the White House.

His transition teams have gone throughout the government to prepare for the new administration, but "it's different," not like those he met as CIA director in 1976 when Jimmy Carter's advance guard arrived "saying we're going to find out what's wrong here and change it." Different, too, from "the teams we sent sallying forth in 1980 to go out and undo all the bad things that we had campaigned against."

In contrast, Bush believes his administration needs to "correct one big problem," the federal deficit, then "build on some tremendous successes" of the Reagan years.

"That's at least the approach that I'm going to bring to the job," he said, sipping a cup of Chinese tea. "People understood that when they were voting. They weren't looking for a radical shift." That last thought was a refrain throughout the conversation.

Bush said he envisions no single theme for his first hundred days, no centerpiece drive like the one that won approval of President Reagan's tax cut economic plan in 1981. The initial months usually are the strongest season in a first term, and the most promising for congressional acceptance of proposals from a new administration. That goes double for a Republican president seeking action in a Democratic Congress.

The new president will set out his agenda in his inaugural address on Friday and in an address to Congress early next month. He said the message will not be one of major overhaul, "for very obvious reasons. I've been a part of what we have been doing, what this president, the present president has accomplished . . . ."

The tie to Reagan was on his mind as he performed one of his last vice presidential duties, presiding over the "kind of antiquated drill" in which Congress counted the electoral votes that made him president.

"I was thinking . . . well, this is historically interesting because this is a continuation, hopefully building. There's going to be change, but hopefully a building on what's happened."

Inevitably, then, comes the question of how this new president can put his imprint on an administration he heralds as a continuation of what Reagan began.

"Style, message, people, be yourself," Bush said. "I made my mind up as vice president to do my job one way. But I'm not vice president, I'm president. I'm the one who's calling the shots. I'm the one who's going to set the agenda . . .

"So automatically, that happens. That happens at the time when I put my hand on that Bible and hold my right hand in the air and say that oath. It happens."

Bush said the successes and problems of presidential leadership will continue to be identified with Reagan for a short time, but "in a while, six months from now, that will be identified with me."

For all the problems that will be on his new desk on Saturday morning, Bush said he is excited about the task and eager to confront the agenda.

"If it weren't for this deficit looming over everything else, leave all the rest of the problems in there, I'd feel like a spring colt," he said.