The question seemed perfectly innocuous. A student at a small gathering of college Democrats in Lacey, Wash., asked Teresa Heinz Kerry why her husband had waited so long in the Senate (almost two decades) before deciding to run for president. The candidate's wife suddenly recalled something her mother had told her: that the Devil was powerful not because "he's so smart--he's so smart because he's so old."

John Kerry as the Devil? For a moment, it looked like the sort of unfortunate, oddball blurt that makes campaign handlers cringe. Kerry's staff has long been uneasy about Teresa Heinz, a demanding, somewhat unpredictable 65-year-old demi-billionaire. But no one in the audience seemed to mind or even notice a sinister juxtaposition. The crowd laughed with her. Perhaps it was the context, an entertaining monologue about her roots in colonial Africa, delivered in her trademark, slightly sexy, vaguely exotic accent. Or perhaps it was just a friendly crowd, Democratic activists who want to believe that Kerry is the One. In any case, the audience appreciated her bluntness when she finally got around to answering the question. "You know what?" she said. "I don't think he was ready."

When John Kerry first declared for president a year ago, the conventional wisdom among Washington know-it-alls was that wife Teresa (pronounced Tehr-AY-zuh) would be a loose cannon who would drive away voters. She was widely seen as imperious, long-winded and way too outspoken about her various causes and charities (as well as about her husband's shortcomings). But as she traveled around the country on her husband's behalf, she has been charming and winning. Her three sons and his two daughters (all in their 20s and 30s) have, after an understandably bumpy merger, come together as attractive friends and step-siblings. The Heinz Kerry family is not exactly the Brady Bunch. But it is an interesting and involved family that has become a significant asset in the campaign.

Teresa Heinz Kerry (she started using his last name after he decided to run for president) is certainly complicated. She can be neurotic and a little loopy, a bit of a hypochondriac, say her friends, and she is not always considerate of her staff. But she has been a prodigious and effective worker, running the $1.2 billion foundation left to her by late husband, ketchup heir Sen. John Heinz, who died in a plane crash in 1991. She can be painfully earnest and self-involved, but also earthy and funny. And she has been good for her second husband, John Kerry.

When she married Kerry in 1995, he had been dating widely but apparently not happily, going out with younger women and starlet Morgan Fairchild. He has described his long separation and eventual divorce from Julia Thorne in 1988 as "painful," and he was constantly scrambling up to Boston to see his two young daughters. In an interview with NEWSWEEK last week, Teresa Heinz spoke of the early years of their marriage almost as though she were domesticating a wounded animal, which in a sense she was. "He had his 'pad'," she says, almost making quote marks as she described Kerry's apartment. "He was always traveling or going up to the schools to see his daughters. It's not like he had a home where he went for the weekend or could invite friends over. There wasn't that kind of sense of..." She pauses. "My sense of living... He was a gypsy. It was hard, climatizing someone who didn't have that regular life--to give him a sense of one place."

Melding the two families--Teresa had three sons by John Heinz--was difficult. Everyone seems to agree that there was friction between Kerry's two daughters, Vanessa and Alexandra, and their new stepmother. Chris Heinz, Teresa's youngest son, spoke to NEWSWEEK of "Oedipal" conflicts. Teresa credits her husband with helping smooth over the rough patches. "Very delicate, actually," she says of his approach. In his own gentlemanly way, Kerry tried to fit in while letting the Heinz boys know that he was not out to replace their father. While Kerry and Teresa were living together--but before they were married--Kerry went out to the Heinz family house in Sun Valley, Idaho. Chris Heinz observed that Kerry and his mother were sleeping in separate bedrooms--out of consideration, Chris believed, for the feelings of the boys. Kerry brought reversible red and green jerseys for Heinz family pickup broom-hockey games. One side, bearing the Heinz ketchup logo, was labeled pickles, the other side, tomatoes.

Chris Heinz, 30, and John Kerry are especially close, playing sports together and talking about history. But all the kids get on. Vanessa, 27, a Harvard medical student, and Alexandra, 30, in film school, have stumped for their father. Andre Heinz, 34, is an environmental consultant who cracks up the traveling press with Bill Clinton and Bob Dole imitations. John Heinz IV, 37, a teacher with a wife and child, avoids the spotlight.

At times, Teresa's outspokenness has made Kerry squirm. A widely read Washington Post piece in June 2002 pictured Teresa ranting about her pet peeves while Kerry tried, awkwardly and not very effectively, to hush and soothe her. To some, Kerry seemed henpecked, if not emasculated, by his wife's willfulness. But Kerry was also humanized by the story; he did not seem like the stiff Brahmin politician of his TV appearances but rather an uncertain but good-willed husband trying to cope. Teresa, say her friends, was devastated by the exposure.

She can still be indiscreet and moody, but she is more disarming than haughty these days. For years after she married Kerry, she continued to refer to the late Senator Heinz as "my husband." Now she is more careful to call Heinz "my late husband." In Seattle last week before a large crowd of Democrats, she stumbled and referred to Heinz again as "my husband." But she laughed (and the audience laughed with her) that she sometimes gets confused because "there are two Johns--John One [Heinz] and John Two [Kerry]." Now she is bracing herself for GOP smears aimed at her wealth. "If they keep doing this to people, they are not going to get anyone but thugs to run for office," she told NEWSWEEK, her eyes flashing. "And I will say that! I'm not afraid! I'm not afraid." No one should doubt her.