Mrs Trump and her son, 11, had stayed in New York to finish the school year.

The decision was seen as unusual by some, as she was the first presidential spouse in recent years not to relocate to the capital immediately.

Separately Mr Trump's daughter, Ivanka, said in a TV interview that her father had been "subjected to a level of viciousness that I was not expecting".

In an interview with the Fox and Friends morning TV show, she said that she had been left blindsided by the ferocity of some of the attacks levelled against the president.

Image copyright AFP

Image caption Ivanka Trump and her husband Jared Kushner (pictured) are both presidential advisers

Ms Trump said that she felt "very vindicated" by former FBI Director James Comey's recent Senate testimony because it supported her father's contention that he was not being personally investigated for alleged links to Russia and that Mr Comey had on at least one occasion supplied a leak to The New York Times.

A Fox News report said that Ms Trump - who along with her husband Jared Kushner is a special adviser to the president - "glided past the more controversial interview topics like a seasoned vet".

Delighted by the move

Melania Trump is the first presidential spouse in recent history to delay her arrival in Washington, following her husband's inauguration at the start of the year.

Her predecessor, Michelle Obama, even moved to Washington early to get her daughters settled in their new school.

However, it seems the First Lady is delighted by the move, tweeting a picture looking out across the White House lawn, marking the occasion.

Image copyright Twitter/@FLOTUS

The move will also no doubt be welcomed by New Yorkers, who have footed a hefty security bill keeping the First Family safe in Trump Tower.

Their presence in the Big Apple has also been known to create a fair few traffic problems. The New York Post warned of a potential "traffic apocalypse" if they did not make the move.