Time magazine, in a cover story this week about Nancy Reagan, says the 63-year-old first lady has moved President Reagan from the far right toward the political center because "more than anything else, she wants the public to continue adoring her husband."

The cover portrait of Mrs. Reagan was painted for Time by Aaron Shickler, who also painted Jacqueline Kennedy's official White House portrait. The magazine says Mrs. Reagan is no longer the "liability" she once was for President Reagan and may even have become a "political plus."

"Within the administration, she has consistently allied herself with the moderates against the conservative ideologues," the story says. "It is not that she is a crypto-liberal. Rather, like Deputy Chief of Staff Michael Deaver and Chief of Staff James Baker, she has instincts attuned more to public relations than to undiluted principle."

Time supports the recurring thesis among Washington's news establishment that Mrs. Reagan is an influential force inside the Reagan White House and sometimes affects policy. The story cites her role in several behind-the-scenes power plays that led to the dismissals or transfers of national security adviser Richard Allen, Secretary of State Alexander Haig and national security adviser William Clark.

Clark, a longtime Reagan aide who had succeeded Allen at the National Security Council, fell from Mrs. Reagan's favor in 1982, partly because of his fidelity to hard-liners at the Pentagon, according to the report. She wanted Clark transferred to Interior but was beaten to the punch when Clark volunteered to go. Especially sensitive to talk of her husband being a saber-rattling militarist, she urged the president to put forth his peaceful intentions.

"I would say, you know, 'This is unfair. It's not right. You are not trigger-happy,' " she is quoted.

More recently, as talk of White House staff changes persisted, Mrs. Reagan reportedly told allies in the West Wing that she did not want Clark to return there. Last week, Clark spared everybody the infighting when he announced he would resign from government and return to California.

Denying that her influence is pervasive, Mrs. Reagan said: "I read that I make decisions and I'm the power behind the throne, and that I get people fired. I don't get people fired."

But Time counters Mrs. Reagan's remarks with one from her son, Ron Reagan, who says her political instincts "are better than my father's in a narrow sense. He has great instincts on a whole country kind of level, the big picture. She's got great instincts when it comes to individuals and small groups. That's why she's involved in the inner workings of the staff at the White House."

Ron Reagan also seems to have settled once and for all the question of Nancy Reagan's age.

"Her personality and values don't necessarily fit in with what a lot of people consider to be those of a contemporary woman," says Ron. "When she first got to Washington, people did not like the idea of a woman who said, 'My life began with Ronnie.' That's not a real popular notion these days, but she feels it. This is a woman who was born in 1921."

Aides to Mrs. Reagan, who have repeatedly given her birth date as July 6, 1923, could not be reached for comment last night.

The story also says that:

Mrs. Reagan wants to expand her anti-drug-abuse campaign by taking it overseas in conjunction with first ladies of other countries interested in establishing similar programs;

Her alma mater, Smith College, once refused White House feelers about conferring upon her an honorary degree;

Mrs. Reagan has deliberately altered "the gaze," the way she looks at the president. "I am trying not to do it as much as I have done it in the past," she said, "only because there was so much talk about it and it was kind of ridiculed."