One former White House aide claims the first lady is “counting every minute” until Trump the president becomes Trump the private citizen again.

The Trumps have “a transactional marriage” and things are so bad they sleep in separate bedrooms in the White House, a former friend and adviser alleged in a new book.

It is claimed Mrs Trump renegotiated her prenuptial agreement before joining her husband in Washington, and last year a divorce lawyer estimated that she could get more than $50 million (£38 million) – far more than what Mr Trump’s first two wives received.

Amid the speculation, Mrs Trump, 50, showed a united front when she appeared to back up her husband’s unsubstantiated claims of voter fraud after he lost the election to Democrat Joe Biden who will be sworn in in January.

She tweeted: “The American people deserve fair elections.

“Every legal – not illegal – vote should be counted. We must protect our democracy with complete transparency.”

The couple first met in 1998 at a party in Manhattan where the newly separated Mr. Trump, now 74, asked then-fashion model Melania Knauss her telephone number.

She has said she rebuffed his initial advance because he was with a date that night.

But by the next year, they were a couple.

The pair got married in January 2005, and had their son Barron in 2006, the year she became a US citizen. Barron is now 14.

She is the third wife of Mr Trump, a dad-of-five who is 24 years her senior.

His first marriage to Czech athlete and model Ivana Zelnickova officially ended in divorce in 1992 after the couple had three children, Donald Jr, Ivanka and Eric, all of whom have played public roles during their father’s first term.

A second marriage to actress Marla Maples in 1993 gave Mr Trump another daughter named Tiffany. The couple separated in 1997 and divorced in 1999.

He had prenuptial agreements with both.

Ivana Trump, now 71, reportedly received $14 million, a mansion in Connecticut and an apartment in Trump Plaza as part of their divorce.

Ms Maples, now 57, is reported to have received a $2 million settlement.

If Mr Trump’s third marriage ends in divorce, Melania could be in line for a lot more money than her husband’s first two wives.

In December last year, divorce lawyer Jacqueline Newman, a managing partner at Manhattan-based Berkman Bottger Newman & Rodd, suggested Mrs Trump could receive about $50 million.

Ms Newman told Town & Country “In this situation, if she has $50 million, she can afford to buy something.

“But $50 million, while it’s definitely a lot of money, in New York City, for what she’s used to, she wouldn’t be able to replicate what she has now.

“He probably had a good sense of what kind of lifestyle they’d be living, so I would imagine the payout would be fairly generous.”

In its 2019 billionaires ranking, Forbes estimated Trump’s net worth at $3.1 billion and 715th in the world.

But his finances have remained a subject of intense scrutiny, culminating in bombshell reports from the New York Times after the newspaper leaked his tax returns, which he refused to make public as is custom for the president.

The newspaper’s articles disclosed that he paid just $750 in federal income tax both in 2016 and 2017. It also revealed “chronic losses and years of tax avoidance”.

Painting a dire financial situation approaching for Mr Trump, the reports added that hundreds of millions of dollars in loans will come due in the next four years.

There was even speculation that his run for president may have been a gambit to revive the marketability of his name

When Trump entered the White House in January 2017, his wife didn’t join him until five months later.

Addressing speculation there was trouble in the marriage, she claimed she didn’t want to interrupt then 10-year-old Barron’s school year.

However, a new book by Washington Post journalist Mary Jordan claims Mrs Trump delayed moving to the White House as leverage for renegotiating her prenuptial agreement.

She needed time to cool off after details about the president’s alleged sexual indiscretions emerged. She learned new details from the media coverage, it was claimed.

She took that time to “amend her financial arrangement with Trump – what Melania referred to as ‘taking care of Barron’,” Ms Jordan wrote in The Art of Her Deal: The Untold Story of Melania Trump.

Her original prenup had not been very generous, and the new agreement ensured that Barron would not be shut out of the family business, the book claims.

During the 2016 campaign, Trump faced allegations of sexual assault, inappropriate sexual behaviour and affairs with a porn star and Playboy Playmate in multiple incidents over about 30 years.

A recording emerged in which Trump bragged about using his celebrity to try to have sex with women and groping them.

In a 2005 conversation with the US daytime TV programme Access Hollywood, he said: “When you’re a star they let you do it. You can do anything.”

He told presenter Billy Bush when he meets beautiful women he feels able to “grab them by the p****”.

In her 2018 book Unhinged, former Trump aide and The Apprentice contestant Omarosa Manigault-Newman claimed Mrs Trump is eager to divorce the president.

She wrote: “In my opinion, Melania is counting every minute until he is out of office and she can divorce him.”

It is said that Slovenia-born Mrs Trump, America’s second foreign-born first lady never expected her husband to win in 2016 and she burst into tears when he defeated Hillary Clinton.

Stephanie Winston Wolkoff, a former close friend and confidant of the first lady, and author of the book Melania and Me, claimed the Trumps had separate bedrooms in the White House and “a transactional marriage”.

According to her profile on the White House website, Mrs Trump is “first and foremost a mother and wife”.