John and Cindy McCain about 10 years ago with their children: from left, Meghan, Bridget (adopted from Bangladesh), Jimmy and Jack.

By JODI KANTOR and DAVID M. HALBFINGER

Cindy McCain was new to Washington and not yet 30 when she arrived at a luncheon for Congressional spouses 25 years ago to discover a problem with her name tag.
It read “Carol McCain.” That was the well-liked wife John McCain had left to marry Cindy, to the disapproval of many in Washington.
Fearing that the slight was intentional, she sat at a half-empty table that never filled. “No one wanted to sit at her table,” said Barbara Ross, a friend who was not surprised when Mrs. McCain announced a few months later that she was moving back to Arizona. “It was like high school.
Cindy McCain, the wife of the Republican presidential nominee, has spent the last year pursuing a return to Washington: “a harsh town” that does not suit her, she has said. Mrs. McCain, 54, describes herself as her husband’s best friend, though for the last two decades they have mostly lived apart .
From the beginning, John and Cindy McCain had two entirely different experiences of Washington. He was the most popular member of the incoming Congressional class of 1983, with the most heroic background, the most uproarious jokes and, from his days as the Senate’s Navy liaison, the highest-level contacts. “John was clearly the star from the first day,” said Steve Bartlett, a former congressman from Texas.
Mrs. McCain was 28, nearly two decades younger than her husband and just five years older than his eldest son. “Cindy was a little bit star struck by John’s fame and the strength of his personality,” said Diana Dunn, who socialized with the couple.
Carol McCain was still a presence on the social scene, working in the Reagan White House and as an events planner. Everyone knew her story: she had stood by her husband during his captivity in North Vietnam, never passing word of a debilitating car accident, only to discover, a few years after their reunion, that he was leaving her for a younger, richer woman.
Cindy McCain announced she was returning to Phoenix to start a family. (They have four children, including a daughter Mrs. McCain adopted in Bangladesh. Mr. McCain has a daughter and two stepsons from his first marriage.)
Ever since, the McCains have led only partly overlapping lives, with Mr. McCain - who was first elected to the Senate in 1986 - spending the week in Washington. Mrs. McCain expanded her childhood home, turning it into a 930-squaremeter mansion . On the walls, she hung photos of the storied McCain military clan and her husband clasping hands with Republican presidents.
When Mr. McCain was home, the two were “as affectionate as you can be with John McCain,” said Wes Gullet, a former aide, explaining that his old boss, with his military training, restless energy and sarcastic humor, is not the cuddly type. Recently, Mrs. McCain has called the separations painful, volunteering that she endured several miscarriages alone. She spent subsequent pregnancies mostly confined to home, Ms. Ross said .
She initially seemed like an ideal political partner, giving Mr. McCain a home state, money and contacts that helped start his career. But as the years passed, she also became a liability at times. Even her fortune from her family’s beer distribution company is a problem in a presidential race that hinges on economic anxieties.
In the Keating Five savings-and-loan scandal in 1989, Mr. McCain was accused of improperly intervening on behalf of a donor, Charles Keating, whose failed savings and loan had cost taxpayers billions. Four other senators were implicated, and one Senate spouse: Mrs. Mc- Cain. She and her father had invested in a shopping center with Mr. Keating . Mrs. McCain busied herself with the American Voluntary Medical Team, a charity she founded to supply medical equipment and expertise to some of the neediest places on earth .
In 1994, Mrs. McCain dissolved the charity after admitting that she had been addicted to painkillers for years and had stolen prescription drugs from it. She had used the drugs, first given for back pain, to numb herself during the Keating Five investigation, she confessed to Newsweek magazine. “The pills made me feel euphoric and free,” she wrote in an essay.
Friends say that campaigning is not easy for her. She has done relatively few solo events during Mr. McCain’s presidential run, grants interviews reluctantly - she declined to speak for this article - and in introducing her husband at events, she offers few of the heartwarming anecdotes that are the normal fare of the political spouse.
Mrs. McCain has said that the smears during her husband’s 2000 presidential bid - he was accused of fathering a black child, a twisted reference to their daughter from Bangladesh - left her skittish about presidential politics.
Observers of that campaign and the current one say she seems different this time - more guarded, more tense, superthin. Physically, she seems fragile: she suffers from migraines, hobbled around on crutches last year and recently wore a wrist brace because of a handshaking injury.
But as her husband’s poll numbers have slid behind Senator Barack Obama’s, her devotion has seemed only to grow. “She would walk on broken glass barefoot if it required her to do so in this campaign,” said Matt Salmon, a former Arizona congressman who knows the couple.