Ronald Kessler, a former Washington Post and Wall Street Journal investigative reporter and a longtime friend to President Donald Trump, is the author of upcoming book, The Trump White House: Changing the Rules of the Game.

In an exclusive excerpt from the book below, Kessler writes that Melania Trump has a special relationship with the president and how she's thrived in her new role as first lady.

More than previous first ladies, Melania accompanies her husband on trips to express empathy for victims of natural disasters such as hurricane Harvey that hit Texas, Irma that hit Florida, and Maria that hit Puerto Rico. But Melania's most important role never comes out.

'She is a very powerful behind-the-scenes force,' Sean Spicer tells me. 'I don't think people fully recognize how influential she is and what a grounded political sense she has on her own.' Spicer says, 'There are times when you're in the room and see it, and she'll weigh in on a decision, and it's not just a yes or no. Instead, it's, look, based on this scenario, here's what makes sense.

In the upcoming book The Trump White House: Changing the Rules of the Game, longtime Trump friend Ronald Kessler tells how Melania Trump has become a powerful first lady. An independent thinker

'She always seems to have the pulse on the right move and the right person at the right time. When she weighs in, it's always spot-on. She knows where he is, where he should be, and how we could move an issue.'

Whether in the Oval Office, on Air Force One, or in the residence, 'When she's around and she feels strongly about an issue or an event or whatever it is, she'll make her position known,' Spicer says. 'The thing is she really thinks about his positioning. Melania knows how to sort of read him and read the situation. She will say, "This is not good for you. This is not consistent with what you said." She really has his best interests at heart. She knows when to pick her battles, and she's always entirely right.'

Melania reads widely, both publications and articles on the Internet. As she said to me at Mar-a-Lago while sitting next to Trump at dinner, 'I read every one of your articles,' referring to the ones I send her.

Melania gives Trump both positive and negative articles that she thinks he should read. She also tips him off to people who come off well on TV in support of him.

An independent thinker, Melania does not necessarily take sides with one faction or another within the White House staff.

However, 'Melania didn't want Ivanka or Jared or other people coming and seeing the president up in the residence for business. She definitely put her foot down on that,' Bannon says.

'I think Melania does all the stuff of being a first lady because she's just very proud of it,' Bannon says. 'She's very low-key. She's not the type who's doing over-the-top waving. She never tries to draw attention to herself.'

While Melania often agrees with the advice of aides, 'Sometimes she'd be the first one to weigh in with a point,' Spicer says.

Kellyanne Conway called Melania 'briliant' and said she had 'amazing instincts, political and otherwise'. Sean Spicer, meanwhile, called Melania a 'powerful behind-the-scenes force' in the White House

Steve Bannon said that Melania can tell who's 'looking out for themselves and not Trump'. Reince Priebus said that Melania will tell Trump when he needs to stop tweeting

In some cases, she will let an aide know that she is on his or her side when that person is under attack from her husband and presumably will let Trump know how she feels as well.

Melania lets Trump know when her intuition tells her an unsavory character is trying to gain access or take advantage of him.

'Melania knows who the bulls*** artists are,' Steve Bannon says. 'She knows the promoters, the guys looking out for themselves and not Trump, and she lets him know it.'

He adds, 'You could write something negative about the president. If it had justification, she'll show it to him.'

'Those of us who have the privilege to know her and work with her also acknowledge and appreciate how brilliant she is,' Kellyanne Conway says of Melania. 'She has amazing instincts, political and otherwise. She reads people exceedingly well. Her own story as an immigrant who heard about this wonderful place called America is inspiring.

'She was a little girl in Slovenia and came to this country to pursue her dreams. She is a successful entrepreneur in her own right, and is a devoted wife and mother.'

Stunning though she is, Melania is modest. 'Great pictures! But not the best of me,' Melania wrote to me, using a smiley face, of a photo of the two of us at a Trump New Year's Eve party at Mar-a-Lago.

Unlike either Laura Bush or Michelle Obama, Melania interacts with aides and discusses policy questions, helping to focus policy or strategy

All first ladies influence their husbands and their administrations to some degree.

In the case of Laura Bush, 'If it's a particular interest of the first lady, we will pay attention to the funding for those programs, and they will always prevail,' Clay Johnson, George W. Bush's high school friend and Yale roommate who became deputy director of the Office of Management and Budget, told me for my book Laura Bush: An Intimate Portrait of the First Lady.

Johnson said Laura's influence extended beyond budgets. OMB routinely asked for her opinion or suggestions on appointments and on issues affecting agencies that deal with subjects of interest to her, such as education, the arts, women's rights, AIDS, libraries, the humanities, and juveniles with social problems.

Bush himself also bounced policy questions off Laura. 'I don't believe he sits down with her and says, "I have six policy items I want to go over with you,"' Johnson said. 'Rather, issues come up in informal conversation. She is very smart and very wise and can give him an objective, big picture perspective that after an hour or so with the policy people, he may have lost.

'As an example, the president will talk to her about civil service reform issues. She will say, 'Do you really want to do that, or do you really want to make a change in leadership at a time like this?' '

Secret Service agents were dismayed to overhear Michelle Obama push her husband to be more aggressive in attacking Republicans and to side with blacks in police shooting controversies.

Kessler, pictured above with Melania at a Mar-a-Lago event, is a longtime friend of the Trump family

Kessler, pictured above with Trump, is also a former Washington Post and Wall Street Journal investigative reporter

Having listened to their talk in the presidential limousine, a former Secret Service agent says, 'Michelle's agenda goes back to when she said about her husband running for president, 'For the first time in my adult lifetime, I am really proud of my country.'

Unlike either Laura Bush or Michelle Obama, Melania interacts with aides and discusses policy questions, helping to focus policy or strategy.

While Laura is a devoted reader of literary works, Melania devours articles on current events and policy issues.

Kessler's The Trump White House: Changing The Rules Of The Game will be released on April 3

Melania also took control of events on the White House grounds, saying all planning and scheduling must go through her.

Melania has confided to aides that she tries to get Trump to cool it when he feels he is under attack and a counterattack will only make things worse, calling more attention to the problem.

A prime example of his self-destructive tendencies was Trump's decision to bring pointless legal action to stop the publication of Michael Wolff's book Fire and Fury, hyping its sales. Sometimes Trump listens; most of the time he does not.

The one piece of advice Trump has never followed from Melania is her constant suggestion that he stop sending tweets to his forty million followers, the greatest number of any world leader.

'She would tell him that he shouldn't tweet so much, put the Twitter away, just do not tweet,' Reince Priebus says. 'No tweeting. Stop tweeting. Slow down on tweeting.'

'That might be one area where she won't win,' Spicer says. 'But that's probably the only one.'

At his age, Trump is 'not about to change,' says Trump's friend Chris Ruddy, CEO of Newsmax Media and a member of Mar-a-Lago.

'He won't stop saying things that rub people the wrong way. And he will not stop tweeting—nor should he—though perhaps there should be a process for reviewing his tweets before posting.'