The author of an upcoming sneak look inside the Trump White House said adviser Kellyanne Conway is the “number one” leaker in the White House.

Author Ronald Kessler also claims in “The Trump White House: Changing the Rules of the Game” that President Trump knows that daughter Ivanka and her husband Jared Kushner bring “problems” but can’t fire them because they’re family.

In a Sunday interview with CNN, Mr. Kessler said Ms. Conway, a counselor to the president and a former campaign manager, has grown so accustomed to leaking that she once forgot an interview was on-the-record as she “dissed” Ms. Trump and Mr. Kushner and said some “mean, cutting and honestly untrue” things about former chief of staff Reince Priebus.

“So if you wonder why there are so many leaks out of the White House, one reason is Kellyanne Conway is the number one leaker,” Mr. Kessler said Sunday.

According to CNN, Mr. Kessler wrote in his book, which comes out Tuesday, that “Jared and Ivanka would push the most disastrous and foolish decisions of Trump’s presidency … they had no understanding of the basic fundamentals of how government works, how a campaign works, how politics works. Most of all, they had no understanding of the political consequences of their actions.”

Asked to elaborate on some of those “foolish decisions” Sunday on CNN, Mr. Kessler said they “pushed the firing of [then FBI-director James] Comey, which was disastrous,” and were behind picking Anthony Scaramucci as White House communications director, which Mr. Kessler called “the most absurd hire in the history of the White House.”

But despite, Mr. Kessler said, Mr. Trump seeing them as “problems,” firing family members would be out of character for the president.