The United States President Donald Trump's niece Mary Trump is also one of his most vocal opponents and is set to publish a tell-all about the Trump family next month.

The 240-pages book titled "Too Much and Never Enough" set to be released on Tuesday, July 28 by Simon & Schuster. The publisher announced the news on Monday. The book is a "revelatory, authoritative portrait of Donald J. Trump and the toxic family that made him." The cover of the book features a photo of the US President from his high school yearbook in the early '60s, reports People.

"She describes a nightmare of traumas, destructive relationships, and a tragic combination of neglect and abuse. She explains how specific events and general family patterns created the damaged man who currently occupies the Oval Office," further reads the description of the book written by Mary, who is also a trained psychologist.

The publisher also noted that Mary "brings an incisive wit and unexpected humor to sometimes grim, often confounding family events" and is, among her family, "the only Trump willing to tell the truth."

Donald Trump and the White House have not yet commented on Mary's memoir, even though they have frequently pushed back other such books about the 73-year-old in the past. However, a source has claimed to Daily Beast that the POTUS is "looking to sue his niece" over the book as she reportedly signed a non-disclosure agreement in 2001 banning her from talking about her relationship with her uncle.

Mary is the daughter of Fred Trump Jr, the president's older brother, who died in 1981 at the age of 42 due to complications from alcoholism. In her memoir, she also writes of "the strange and harmful relationship between Fred Trump and his two oldest sons": her father -- Fred Trump Jr., and the president.

US President Donald Trump
US President Donald Trump Photo: AFP / SAUL LOEB

"She recounts in unsparing detail everything from her uncle Donald's place in the family spotlight and (first wife) Ivana's penchant for regifting to her grandmother's frequent injuries and illnesses and the appalling way Donald, Fred Trump's favourite son, dismissed and derided him when he began to succumb to Alzheimer's," read the description.