In the interviews, she also called civil rights leader Martin Luther King Jr. "terrible," "tricky" and "a phony."
"This book shows Jackie Kennedy unplugged," historian and CBS News analyst Douglas Brinkley told "Early Show" co-anchor Erica Hill Monday.
He said, "A lot of the rawness of her feelings, I think, as a young woman -- she's is only in her 30s when she is doing these tapes in 1964 -- is very different from the more poised and discrete Jackie Kennedy we got to know in the 1980s and 1990s."
She said her husband and his brother, then-Attorney General Robert F. Kennedy, a longtime LBJ antagonist, even discussed ways to prevent Johnson from winning the Democratic nomination in a future contest.
The book, "Jacqueline Kennedy: Historic Conversations on Life with John F. Kennedy," includes a series of interviews the former first lady gave to historian and former Kennedy aide Arthur M. Schlesinger Jr. shortly after her husband was assassinated on Nov. 22, 1963.
Over seven sessions, she recalled conversations on topics ranging from her husband's reading habits to the botched Bay of Pigs invasion in Cuba.
JFK increased the U.S. presence in Vietnam throughout his brief administration, adding military advisers to help train the South Vietnamese military. Johnson, as president, would later commit ground troops to the conflict despite initial promises not to. Historians still debate whether Kennedy would have done the same.
Jacqueline Kennedy spoke skeptically of King.
She called him "tricky" and a "phony" after hearing about FBI tapes of him and a woman in his hotel room, while noting that JFK had urged her not to be judgmental. (JFK's own adulterous affairs weren't yet widely known.)