NAME: Craig Fuller. AGE: 35. OCCUPATION: Public affairs and public relations professional. OFFICIAL ROLE IN BUSH CAMPAIGN: Chief of staff to the vice president. UNOFFICIAL ROLE: Protector of the candidate, or The Man Who Must Say No.

If power in Washington is measured in terms of one's closeness to the principal, then Craig Fuller has managed to become one of the more powerful people around George Bush in a very short time.

He's the one staff member who sits with George and Barbara Bush in Air Force Two's stateroom, controls virtually all access to the vice president on a daily basis and, for that matter, is rarely far from Bush's elbow himself. Even his office is in the same suite as the vice president's -- much closer than that of his predecessor. Call him the Mike Deaver of the Old Executive Office Building.

"Craig Fuller is a very ambitious man," observes one Republican operative. "He just won't let the body out of his sight."

For Fuller, that involves ricocheting around the world in the relative luxury of Air Force Two as Bush talks of Nicaragua in Nashville and of oil in Saudi Arabia. This, of course, is all under the guise of campaigning for Republicans in '86 races or fulfilling official vice presidential duties -- which annoys his presidential rivals, who would love the same visibility.

It is Fuller's job to shape Bush's message from week to week, and he'll help Bush decide when to cease being a salesman for administration policies and begin to clearly define his own positions.

"At some point they need to set out a clear-cut agenda that is consistent with the Reagan program but that starts defining a new era," says Ken Duberstein, former chief White House congressional liaison, now a lobbyist.

But not yet, says Fuller. Bush "doesn't feel it's necessary . . . I think a fair question to ask is whether people are really listening to him now . . . "

Even though some of Bush's own people worry that voters have little sense of him as his own man? And that too much boosterism may add to his image as a wimp?

"Well, we're not going to go out and manufacture some event and have him deck someone!" Fuller responds. "There's not much we can do. I think you dispel it over time . . . Crazy notion for someone who has been a fighter pilot."

Bush and Fuller have forged an unusually close bond in the year since Fuller signed on, but that's not to say his life has been easy.

He has gone from being viewed as a diplomatic White House staffer (he was assistant to the president for Cabinet affairs, skillfully juggling competing Cabinet demands) to being criticized more than any member of Bush's staff. His detractors complain that he is a poor manager more interested in blocking access to Bush than getting the job done.

The most serious charge? That he doesn't return phone calls -- a deadly sin in a business that keeps AT&T afloat.

Last December, when William F. Buckley invited both Bush and Reagan to attend the 25th anniversary party for National Review, the president's office responded -- positively -- within three days. A source close to Buckley says the columnist was furious because he had to call the vice president's office himself to get a response. Fuller then told him that Bush was too busy to come.

Worse yet, shortly after Fuller first assumed the chief of staff job, word got around that he'd failed to return a call to Jim Baker.

Not exactly, Fuller explains: When Baker phoned, Fuller was eating lunch in the White House mess, and Baker left a message asking that Fuller not be disturbed. By the time Fuller reached him three hours later, Baker had already called the vice president himself. "Even Craig's greatest critics wouldn't call him stupid," says Fred Khedouri, assistant to the vice president for policy. "Practically anyone in the country would call back Jim Baker."

"All those people I call every day must feel very good when they read I don't return calls," says Fuller. "A large part of my responsibility involves my being with the vice president . . . It's just physically impossible for me to return 70 or 80 phone calls a day."

Still, the access problem got bad enough that Robert Mosbacher implored Fuller to hire an assistant, which he did. Last week David Bates, a personal aide to Bush during the 1980 race, came on as a deputy chief of staff. His job: Return those calls and keep the loyalists happy.

A native Californian, Fuller came to the Reagan White House as a prote'ge' of Mike Deaver, for whom he had worked at Deaver's old public relations firm in Los Angeles. In fact, Fuller had plans to resume work with Deaver outside the government last year before Brady, Atwater and Teeter thought of him for the chief of staff job. He's married to Karen Hart Fuller, his former executive assistant at the White House, who now holds the same job for White House Communications Director Pat Buchanan. In his spare time, he flies his own plane.

As '88 approaches, Fuller will no doubt stick close to "the body" on the campaign plane, while continuing to run the vice president's operation from the inside.

"I thought the model that Jim Baker tried to build during the '84 election -- with me staying on as chief of staff, at the same time having a strong campaign staff -- is desirable," he says.

And does he want to run the campaign from Bush's office, as everyone knows Baker ran Reagan's '84 campaign from the White House?

"I'm not suggesting I'd run the campaign . . . And I don't pretend to have the political experience Jim Baker does."