Let’s get it out of the way right now: Robert Caro’s newest Lyndon Johnson biography does not implicate the former president in the death of John F. Kennedy — and if you could stop asking him about it, he’d be greatly obliged.

Author and biographer Robert Allan Caro is shown during an interview in New York. (Bebeto Matthews/AP)

What the book does address, though, is Johnson’s ascent to the vice presidency, and the first few weeks of his presidency, after he succeeds Kennedy. The book begins in 1958, before the Democratic primary that Johnson lost, and devotes nearly half of its length to the the weeks just before Kennedy’s assassination, when the vice president was frustrated by his powerlessness, having been left out of important decisions.

In one particularly punishing passage, the book sheds light on both Kennedys’ opinions of Johnson during the Cuban Missile Crisis. Wrote Caro: “The people who ‘had participated in all these discussions ,’ Robert Kennedy was to say, ‘were bright and energetic people. We had perhaps amongst the most able in the country, and if any one of a half a dozen of them were President the world would have been very likely plunged in a catastrophic war.’ Lyndon Johnson, he would make clear, was one of that half dozen.” Caro also wrote that Jacqueline Kennedy later wrote a letter about Kennedy’s “diminishing opinion” of LBJ. “As his term progressed, he grew more and more concerned about what would happen if LBJ ever became president. He was truly frightened at the prospect,” she wrote.

Johnson has been a decades-long obsession for Caro, who published the first part of his expected five-part biography in 1982. The New York Times reports that his drafts are handwritten on legal paper — even though the published “The Passage of Power” weighs in at more than 700 pages. Look for the Washington Post’s review of the book later this week.