Publicly, Barbara Bush likes to be thought of as Not Nancy Reagan. She doesn’t want to appear glitzy or manipulative. Indeed, Mrs. Bush is very much a do-gooder. She spends much of her time hugging AIDS babies, campaigning for literacy and feeding the homeless. She is much warmer than Mrs. Reagan and a good deal less ostentatious. For the most part, she has gotten deservedly good press, though in a recent column New Republic editor Andrew Sullivan bitingly referred to her as a “stealth-Nancy in Keds” and accused White House reporters of giving her a free ride.

In her own way, Mrs. Bush, who declined to be interviewed for this article, is just as tough and just as tenacious as her predecessor. Her image may be a cross between Mother Teresa and Auntie Mame, but White House insiders know a shrewder, more complex woman. The portrait that emerges of her after three years in the East Wing is of a funny, sometimes acerbic woman who is genuinely caring-and alway’s in control.

The joke in Washington is that Bush selected Dan Quayle as vice president to ensure that someone at his side would provide an adoring glance. When Bush splutters, the First Lady has been known to wince or roll her eyes. After he was hospitalized for an irregular heartbeat last spring, Bush griped about the brouhaha his illness caused: “I wish I’d never mentioned it.” Mrs. Bush was not sympathetic. “Don’t be dumb, George,” she said. The public affection between the First Couple, after 46 years of marriage, is more teasing than romantic, much more Burns and Allen than Ron and Nancy.

Outwardly, the two divide their labors the old-fashioned way: she runs the house; he runs the world. But her true feeling about her role occasionally slips out. During the Reagan years, she once used the phrase “when we became vice president.” She jealously guards her access to the president’s ear, rarely informing Bush’s top aides of her views. " I don’t have to talk to his staff," she has said. “I’ll tell George.” Friends say she does just that shortly after 5:30 each morning in bed in the White House as she and her husband skim the papers. If he tires of her advice, he lets her know. “That’s enough, Bar,” the president mumbles, raising his hand to end the conversation.

The First Lady represents Bush’s kinder, gentler side, pushing him to be more moderate on civil rights and more compassionate toward AIDS victims. She dodges questions about abortion by saying that she’s pro-children but does little to dispel the widely held notion that she is prochoice. If she sometimes publicly differs from her husband or gets out ahead of him, he usually doesn’t mind. Just as Bush uses Quayle to reach out to the party’s right wing, he understands Barbara’s appeal to moderates. Privately, Mrs. Bush sometimes sounds more like Quayle. Though she would not say so publicly, with friends she denounces gay promiscuity.

Barbara Pierce Bush, the suburbanite Smith girl, was raised to show grace under pressure, and she does. She saved the evening last January when Bush threw up on the prime minister of Japan, by joking that her husband was so unaccustomed to losing at tennis that he fell ill after being trounced by Japan’s emperor and crown prince. She has a biting wit. Her impression of Bush’s 1984 vice presidential opponent, Geraldine Ferraro, Mrs. Bush allowed to reporters, “rhymes with rich.” She once joked that the sight of stretch pan across the ample rear end of a European president’s wife “gives new meaning to the word stretch.” Staffers who are a bit over weight or badly turned out have heard her gibes. When her teasing crosses the line, she shows remorse but rarely apologizes. Instead, she tells her victims the president often takes her aside and says, " Bar, are you sure they know you’re joking.?"

Barbara Bush is fiercely protective of her family and friends, and she is not afraid to let her displeasure be known. White House reporters who write critical stories are familiar with her icy glare. When former chief of staff John Sununu irritated New Hampshire Gov. Judd Gregg, a longtime supporter, Mrs. Bush called a Sununu aide to complain about sloppy staffwork. " Don’t let it happen again," she warned.

Unlike Mrs. Reagan, Mrs. Bush has not left her fingerprints on any dismissals from the White House staff. But at least one cabinet member owes her his job-Dr. Louis Sullivan secretary of Health and Human Services, an old ally on civil rights. Her chilliness toward former White House speechwriter Peggy Noonan may help explain why Noonan decided not to join the Bush campaign. According to campaign staffers, Noonan was not pleased to be asked to write a speech for Mrs. Bush early this year. The First Lady, in turn, did not like the speech Noonan drafted, in part because the former presidents invoked were Democrats. Noonan later said she would be staying in New York for the rest of the campaign season.

Bush never acknowledges that his wife exercises any control over the Oval Office. But when a Department of Education staffer declared in 1990 that minority scholarships were unconstitutional, the First Lady was furious. “George Bush is not a bigot,” she complained to an administration official. “Don’t they realize this makes him look like one?” In less than two weeks, the decision was revoked.

There is not much doubt that Bush is hoping that his wife’s popularity will help his own flagging image. She is, some would say, his only remaining asset. While Bush’s favorable rating has plummeted below 40 percent, the First Lady’s has remained up around 80 percent. When Bush’s aides discovered that voters were not buying Bush’s “Message: I care” line, they tinkered with his stump speech. The president now says, " Barbara and I care" and receives thunderous applause. Worried that Mrs. Bush might lose her halo if she speaks out too strongly, a Bush adviser has warned the First Lady to avoid substance in her speeches. The president’s advisers might do better just to leave her alone. To most voters, she is more believable than her husband.