BIOGRAPHY:He had been derided as a Texas corn pone, but when he became US president, after the assassination of JFK, Lyndon Johnson showed himself to be a consummate strategist with a passion for social justice

The Passage of Power: The Years of Lyndon Johnson By Robert A Caro Bodley Head, 736pp. £35

THEY ARE AMONG the most vivid and haunting images of the 20th century, indelibly etched in our collective memory: John and Jacqueline Kennedy, beautiful as gods, descending the aircraft steps in Dallas on the morning of November 22nd, 1963; the rapturous welcome on the streets of the city; the crack of a high-powered rifle . . .

Robert Caro describes the scene from the point of view of Vice-President Lyndon Baines Johnson’s bodyguard, Rufus Youngblood, who had thrown himself on top of Johnson in the follow-up car, to protect him. “As the third shot had rung out, a little bit of something gray had seemed to fly out of Jack Kennedy’s head,” Caro writes. “Then his wife in her pink pillbox hat and pink suit, that seemed suddenly to have patches of something dark on it, was trying to climb onto the long trunk of the limousine, and then was clambering back into the car, where her head was bent over something Youngblood couldn’t see.”

Less than an hour later Kennedy’s aide Kenneth O’Donnell walked into the cubicle in Parkland Hospital, in Dallas, where Johnson and his wife, Lady Bird, were waiting. Mrs Johnson knew what he was going to tell them the instant she saw the stricken face of O’Donnell, “who loved him so much”.

Johnson had wanted the presidency his whole life. But he was lucid. “For millions of Americans I was still illegitimate, a naked man with no presidential covering, a pretender to the throne, an illegal usurper,” he said years later. “And then there was Texas, my home, the home of . . . the murder. And then there were the bigots and the dividers and the eastern intellectuals, who were waiting to knock me down before I could even begin to stand up.”

Only that morning Johnson had read again the familiar newspaper headlines about his political humiliation and the financial scandals that loomed over him. Transformed by the office that he had so horrifically attained, he shed his hangdog look, took charge, began giving orders. Johnson knew he needed the imprimatur of the Kennedy family. He telephoned the slain president’s brother Robert, the attorney-general and his arch-enemy, seeking Bobby’s blessing for an immediate oath of office. He refused to leave Dallas without Jacqueline and the president’s heavy bronze coffin.

Minutes before a Texas judge, chosen by LBJ, administered the oath of office in Air Force One, the Johnsons sat with the newly widowed first lady beside JFK’s casket. Lady Bird told movingly of their encounter. “Mrs Kennedy’s dress was stained with blood. One leg was almost entirely covered with it and her right glove was caked – that immaculate woman – it was caked with blood, her husband’s blood.”

Despite her shock and grief Mrs Kennedy made the awkward encounter “as easy as possible”, Lady Bird said. “She said things like, ‘Oh, Lady Bird . . . we’ve always liked the two of you so much’. She said: ‘Oh, what if I had not been there. Oh, I’m so glad I was there.’ ”

When Mrs Johnson asked Mrs Kennedy if she wanted to change clothes, the latter replied: “I want them to see what they have done to Jack.”

Robert Caro’s previous four books, including three earlier volumes of Johnson’s biography, have won a Pulitzer Prize, a National Book Award and two National Book Critics’ Circle Awards. To read The Passage of Power is to witness history as it happened: the forces and accidents that shape events, the importance of character.

As US senate majority leader for six years, Johnson was considered the second most powerful man in the US. When Kennedy challenged him for the 1960 presidential nomination, Johnson at first derided JFK as “the boy”, “Sonny Boy” or “Little Johnny”, as just a rich kid whose daddy, Joseph Kennedy, was trying to buy him the nomination.

After losing out to JFK for the Democratic nomination, Johnson accepted the vice-presidential slot in the mistaken belief that he could steal away a measure of presidential power. “Power is where power goes,” he told friends who advised him against it.

In the White House Johnson found himself at war with Bobby Kennedy, whom he referred to as the “snot-nosed brother”. For years LBJ had relished telling the story of how Franklin D Roosevelt sacked Joseph Kennedy, then ambassador to London, in his presence. Bobby loathed him for it. “Did you ever see two dogs come into a room and all of a sudden there’s a low growl, and the hair raises up on the back of their necks?” an LBJ staffer asked Caro, recounting the first meeting of the two rivals, a decade before JFK’s assassination.

Johnson and Bobby Kennedy assumed that JFK would serve two terms, and both hoped to succeed him. Though his civil-rights and tax-cut legislation was log-jammed on Capitol Hill, JFK refused to exploit Johnson’s experience of 23 years as a congressman. Johnson was excluded from the small meetings where important decisions were made, forced to ask permission to use a government jet, and reduced to hanging around JFK’s secretary’s office in the hope of deluding journalists and cabinet members that he was close to the president. White House aides mocked the poor boy from Texas as “Rufus Cornpone”.

Johnson’s hawkishness during the October 1962 Cuban missile crisis, when the US came to the brink of nuclear war with the Soviet Union, deepened his isolation. Jackie Kennedy later wrote to Kennedy’s speechwriter, Ted Sorensen, that her husband was “truly frightened at the prospect” that Johnson could become president.

This book covers the years 1959 to 1964. Caro says he found it “very sad and poignant” to research Johnson’s miserable three years as vice-president. It’s the sort of tale Americans love, of failure and redemption, “a story about what being without power can mean in a city in which power is the name of the game; in a city as cruel as Washington”, Caro writes.

Kennedy’s assassination occurs halfway through the volume, the turning point and hinge of the book. Politicians usually hide their true character, Caro observes, but when they obtain power they reveal it. Johnson, the crude bully and braggart, showed himself to be a consummate strategist with a passion for social justice, exploiting American grief about Kennedy’s death to achieve legislation more far-reaching than anything Kennedy imagined.

Speaking to Congress five days after JFK’s death, Johnson said: “No memorial . . . could more eloquently honour President Kennedy’s memory than the earliest possible passage of the civil-rights bill for which he fought so long.”

The publication of The Passage of Power has coincided with a low point in Barack Obama’s presidency. Though Caro insists his book is about Johnson, Obama is obviously more like the handsome, charismatic Kennedy, who also attempted to win over opponents gradually. When Johnson wanted a Bill passed he worked the White House phone all night, waking up congressmen, whom he flattered, cajoled, threatened, even blackmailed. It’s a skill mastered by neither Kennedy nor Obama.

Johnson declared a “war on poverty” in his first state of the union address, in January 1964. Half a century later his enormous achievements – the Civil Rights Act and Voting Rights Act, which ended racial segregation, the Head Start, Medicaid and Medicare programmes – are again under attack by conservatives. And the war on poverty was lost long ago, swallowed up in the maw of Johnson’s war in Vietnam.

Lara Marlowe is Washington Correspondent