A Secret Service agent who protected Hillary Clinton is set to publish a tell-all book.

Gary Byrne says he was posted outside Bill Clinton's Oval Office in the 1990s and that what he saw 'sickened him'.

His expose is causing deep concern in the White House, according to Drudge Report, and its release comes as Hillary comes within touching distance of securing the Democratic nomination.

The book titled Crisis of Character: A White House Secret Service Officer Discloses His Firsthand Experience with Hillary, Bill, and How They Operate is set to hit shelves on June 28.

The Democratic convention, where Hillary could be confirmed as the nominee, will take place a month later.

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Hillary Clinton is braced for an expose from a Secret Service agent who protected her during Bill's 1990s administration. She is pictured during a campaign event in California on Saturday ahead of the primary

According to Drudge, specific details of the book are being kept under a tight embargo.

A description of the book reads: 'Posted directly outside President Clinton's Oval Office, Former Secret Service uniformed officer Gary Byrne reveals what he observed of Hillary Clinton's character and the culture inside the White House while protecting the First Family.

'Now that a second Clinton administration threatens - their scheme from the very beginning -- Byrne exposes what he saw of the real Hillary Clinton.

'While serving as a Secret Service Officer, Gary Byrne protected President Bill Clinton and the First Family in the White House and outside the Oval Office.

'There, he saw the political and personal machinations of Bill and Hillary Clinton and those who were fiercely loyal to them.

Gary Byrne, the man behind the expose, says he was posted outside Bill Clinton's Oval Office in the 1990s and that what he saw 'sickened him'

'In CRISIS OF CHARACTER Byrne provides a firsthand account of the scandals - known and unknown - and daily trials ranging from the minor to national in scale.

Byrne, who was one of the agents who complained about Monica Lewinsky's behavior, says he wants voters to see the 'real' Hillary before they head to the polls

'Having witnessed the personal and political dysfunction of the Clinton White House - so consumed by scandal and destroying their enemies, real and imagined - Byrne came to understand that, to the Clintons, governing was an afterthought.

'He now tells this story - before voters go to the polls - in the hopes that Clinton supporters will understand the real Hillary Clinton.'

Byrne was one of the Secret Service agents questioned by a Grand Jury about Bill's dealings with Monica Lewinsky in 1998.

According to the Washington Post article published on the hearing Byrne complained to then-White House deputy chief of staff Evelyn S. Lieberman about Lewinsky's actions in 1996.

A short time later Lewinsky was removed from her position because of 'immature and inappropriate behavior'.

He claimed that he saw Lewinsky in the West Wing of the White House when she was not authorized to be there.

The New York Times reported that Mr Byrne also expressed concerns about Ms Lewinsky's after-hours access to the West Wing, which houses the President's Oval Office and the work spaces of the most senior White House aides

Since her husband's administration ended, Secret Service agents assigned to Hillary have slammed her behavior.

In investigative journalist Ron Kessler's explosive book, The First Family Detail, he claims that agents saw her as one of the most detested assignments and believed her marriage to Bill was 'fake'.

It reveals how both current and former agents strongly dislike being on Mrs Clinton's detail, while also revealing how they felt about protecting Chelsea Clinton and Bill Clinton.

His expose is reportedly causing deep concern in the White House and its release comes as Hillary comes within touching distance of securing the Democratic nomination

In the book, Kessler presented Chelsea as someone who not only respected and appreciated her agents, but also was a model protectee.

LIST OF CHAPTER TITLES Chapter 1 - The Vase Chapter 2 - The Air Force Security Police Chapter 3 - Club Fed Chapter 4 - To The White House Chapter 5 - Meet The New Boss Chapter 6 - The Boy From Hope, Arkansas Chapter 7 - 'Billary' Chapter 8 - Clinton World Chapter 9 - Oklahoma City Chapter 10 - Mole Chapter 11 - Wild Bill Chpater 12 - USSS Work Environment Chapter 13 - Tours And JJRTC Chapter 14 - Mud Drag: Part 1 Chapter 15 - Mud Drag: Part 2 Chpater 16 - *Commerce Firing* Chapter 17 - New Skies Chapter 18 - Cyprus (Source: Drudge Report) Advertisement

The former president is described as a difficult chief executive who is also easygoing in the book.

However, Hillary is exposed as being the complete opposite of her husband and daughter, and instead is reportedly very rude and acted nasty toward a number of agents.

'Hillary was very rude to agents, and she didn't appear to like law enforcement or the military,' former Secret Service agent Lloyd Bulman recalled to Kessler.

'She wouldn't go over and meet military people or police officers, as most protectees do.

'She was just really rude to almost everybody. She'd act like she didn't want you around, like you were beneath her.'

On another occasion, a member of the uniformed Secret Service once cheerfully greeted Mrs Clinton by saying 'Good morning, ma'am.'

'F*** off,' is how she replied, according to Kessler's book.

Kessler explained in the book that when Mrs Clinton is in public, she smiles and acts graciously.

'As soon as the cameras are gone, her angry personality, nastiness, and imperiousness become evident,' he wrote.

'Hillary Clinton can make Richard Nixon look like Mahatma Gandhi.'

His book also revealed how Mrs Clinton allegedly didn't like the attire military aides wore.

'Hillary didn't like the military aides wearing their uniforms around the White House,' one former agent recounted to Kessler.

Dan Emmett, who began covering President Clinton on his first day in office in January 1993, said Hillary was arrogant, never said 'thank you' to the agents and treated them like 'hired help'.