In the heady days of JFK and Camelot, young Ivy Leaguers on the Washington social circuit regaled themselves with a snide one-liner: “Whatever happened to Lyndon Johnson?” The answer of course was that LBJ, whose life ambition was to win the office once held by his hero FDR, now occupied instead the mostly ornamental vice-presidency. A once larger-than-life figure, who had mastered the Senate when John F. Kennedy was just an upstart rendering undistinguished service there, had become the butt of cocktail-party humor. That did not sit well with a man driven by the need for power and recognition. By turns sulky and resentful, effusive and sycophantic, Johnson could not accept the fact that, as he once bitterly put it, “my future is behind me.”

Robert Caro, a superb storyteller with a stunningly acute political sense, lays bare the shrewd stroke of genius behind Kennedy’s surprise choice of Johnson as his running mate in 1960. Other, more likely seeming candidates lacked LBJ’s key asset: a Southern pedigree and a political network that could battle old-boy opposition to the presidential ambitions of a northeastern liberal. It wasn’t going to be easy. Texas had gone solidly Republican in 1952 and 1956, and many white Texans fumed about Johnson’s alliance with the “socialist” Kennedy, a man they suspected would assault the beloved institution of segregation. Enter an array of old hands at manipulating electoral outcomes—in particular, a political boss named George Parr, the Duke of Duval County, who in 1948 had produced the “lost” ballot box that cleared Johnson’s rise to the Senate. Did something similar happen in 1960? When Kennedy managed to squeak by in Texas by 2 percent, amid GOP allegations of tens of thousands of fraudulent votes, the state Democratic Party head, Edward A. Clark, flashed a knowing smile and commented, “Our old friends stood by us.”

In office, Johnson set out to accomplish what many others before him had failed to do—remake the vice presidency into a position of consequence. He quickly became frustrated in his plan to secure vice-presidential authority over foreign affairs, and his endless scheming to gain admittance to the president’s inner circle proved fruitless. Soon he was wallowing in self-pity. With silken tactfulness, Kennedy ordered staffers, who privately called the vice president “Uncle Cornpone,” to treat Johnson with respect, and in Cabinet meetings took care to make a show of soliciting his deputy’s advice. But Johnson only furthered his alienation with sad-faced responses, frequently insisting that he had nothing worthwhile to add. When he urged a hawkish response during the 1962 Cuban missile crisis, even as Kennedy was working to orchestrate a tranquil denouement, the gap between them widened. According to the presidential secretary’s records, the two men spent nearly eleven hours in private conference in 1961; in 1963, they spent less than two hours alone.

As in his three previous installments on Johnson’s life, Robert Caro plays the role of biographer-as-archaeologist, excavating details that demonstrate his subject’s complexity. The LBJ we meet in these pages is a politician almost helplessly torn between fear of public embarrassment and an abiding terror of being left out of the spotlight. Caro’s attention to a forgotten scandal of 1963 shows Johnson’s impulse to cover up in the face of unfavorable news. When reporters revealed that his longtime protégé, Bobby Baker, peddled influence for cash and founded a private sex club for lawmakers and lobbyists, Johnson publicly denied their close friendship—and privately took measures to ensure Baker’s silence about the Johnsons’ questionable family finances.

His mutually hostile relationship with Robert F. Kennedy, the president’s brother and attorney general, also yields significant clues about Johnson’s character. On the one hand, we see the pathos of an encounter during a late night of White House partying, when, like an anxious sophomore, Johnson begs RFK to explain why he hates him. On the other is Johnson’s cold cruelty when, upon JFK’s murder, he calls on the shattered RFK to dictate over the phone the presidential oath Johnson would soon take.

Caro’s forthcoming and final volume, covering the bulk of the Johnson presidency—including the astounding legislative achievements of the Great Society and the ill-fated intervention in Vietnam—promises to highlight his subject’s darker angels. Meanwhile, the last third of the current book focuses on Johnson’s triumph over his baser qualities during the first weeks of his presidency. Critical was his ability to suppress deep bitterness and persuade heartbroken Kennedy aides to assist in the epic push to pass a civil-rights bill through Congress—and to launch a war on poverty that would transform American society.

The Passage of Power teaches that while we can’t expect perfection from our political leaders, the hope for redemption remains. Caro admiringly writes that in Johnson’s early days as president he seized the opportunity “to overcome governmental and political obstacles that had stood in the path of social justice for more than a century.” It was, in Caro’s judgment, Johnson’s “finest moment, a moment not only masterful but, in its way, heroic.”