Donald Trump’s most senior aide, chief of staff John Kelly, lifts the lid on chaos in the White House

Donald Trump’s most senior aide has lifted the lid on the turmoil he couldn’t control and made a damning revelation that seriously undermines the President.

He was brought in to be the “adult in the room” — a respected figure who could wrangle Donald Trump, force the President to focus on the big issues and bring an end to the angry tweets and kneejerk decisions.

But as he departs his post as White House chief of staff, John Kelly has delivered a blistering assessment of the administration and painted a picture of constant chaos.

In a wide-ranging interview with The Los Angeles Times, Mr Kelly defended his effectiveness but hinted that there was little more he could have done to bring an end to the turmoil.

And in perhaps the most damning revelation, he admitted that Mr Trump’s controversial border wall — which has seen a government shutdown due to a budget spat — is not really a wall after all.

“To be honest, it’s not a wall,” Mr Kelly told the newspaper.

“The President still says ‘wall’ — oftentimes frankly he’ll say ‘barrier’ or ‘fencing,’ now he’s tended toward steel slats.

“But we left a solid concrete wall early on in the administration, when we asked people what they needed and where they needed it.”

Donald Trump’s most senior aide has revealed the president abandoned plans for a concrete border wall months ago. Picture: Evan Vucci/AP

Mr Trump’s proposed border wall was a key part of his election campaign and, until recently, he vowed it would be tall, made of concrete and virtually impenetrable.

“Jeb Bush just talked about my border proposal to build a ‘fence’,” he tweeted during his campaign in 2015.

“It’s not a fence, Jeb, it’s a WALL, and there’s a BIG difference!”

But yesterday, White House adviser Kellyanne Conway insisted the apparent contradiction was “a silly semantic argument”.

“There may be a wall in some places, there may be steel slats, there may be technological enhancements,” Ms Conway said in an appearance on Fox News Sunday.

“But only saying ‘wall or no wall’ is being very disingenuous and turning a complete blind eye to what is a crisis at the border.”

Building a massive wall along the southern border of the United States was Donald Trump’s key election commitment, and now is unlikely to eventuate. Picture: Guillermo Arias/AFP

His departure comes on the back of the damaging resignation of Defence Secretary Jim Mattis, who released a scathing letter outlining his reasons for exiting, including Mr Trump’s foreign policy views.

Seemingly in retaliation, the President the brought forward Mr Mattis’ end date by two months.

The White House has been dubbed a revolving door for the sheer volume of comings-and-goings of senior aides, advisers and cabinet members.

It was hoped as the President’s right-hand man, Mr Kelly could bring some semblance of order to the administration.

John Kelly finishes in his post as White House chief of staff during a time of immense chaos and uncertainty. Picture: Olivier Douliery/AFP

Mr Kelly was a decorated marine who served for 46 years in conflicts ranging from the Vietnam War to battling the rise of Islamic State.

He was chosen to head Homeland Security before later becoming the President’s chief of staff, a move that unnamed Pentagon officials reportedly said would see him be one of the “adults in the room”.

He again denied damning claims in the book Fear: Trump In The White House by renowned investigative journalist Bob Woodward that he called Mr Trump an “idiot’ on numerous occasions.

But Mr Kelly admitted that on a number of major issues, such as Mr Trump’s executive order suspending the US refugee program for three months, he was not given time to review the details before a swift decision was made.

“I had very little opportunity to look at them,” Mr Kelly said.

Washington powerbrokers hoped John Kelly would be the ‘adult in the room’ but now say he failed to control an unruly and unpredictable president. Picture: Evan Vucci/AP

The explosive Los Angeles Times story cites supporters of Mr Kelly as saying he had to step in to “block or divert” Mr Trump on “dozens of matters large and small”.

Those sources credit him with convincing the President not to withdraw from NATO, as he had threatened, or to remove US troops from South Korea.

Mr Kelly insisted that he provided a wealth of information to Mr Trump before he made a decision, even though the President often insisted he acted on “gut” rather than intelligence.

“It’s never been (that) the President just wants to make a decision based on no knowledge and ignorance,” Mr Kelly said. “You may not like his decision, but at least he was fully informed on the impact.”

His critics told the newspaper Mr Kelly failed to “rein in” a divisive and fiery Mr Trump, including to cease his tendency for late night and early morning angry tweets.

And he failed to bring more order and sense to executive decision making, they said.

However, in his two-hour interview, Mr Kelly said his effectiveness could be marked by what the President did not do under his counsel, rather than what he did do.

Jim Mattis is another high-profile departure from Donald Trump’s administration, resigning as Defence Secretary. Picture: Virginia Mayo/AP

Mr Trump has appointed Office of Management and Budget boss Mick Mulvaney as his acting chief of staff, after a number of potential candidates knocked back the job this month.

He faces a tough task, dealing with the ongoing government shutdown crisis and the fallout from contentious security, border and military decisions.

When the newspaper asked why Mr Kelly stayed for 18 months, despite notable differences and apparent clashes, he said he felt bound by duty.

“Military people don’t walk away,” he said.