Former US ambassador to the United Nations Nikki Haley has accused top Trump cabinet members Rex Tillerson and John Kelly of trying to recruit her to 'save the country' by undermining the president.

Haley, a fierce Trump loyalist, made the allegations in her new book, With All Due Respect.

She claimed that Former Secretary of State Tillerson and former White House Chief of Staff Kelly approached her with a plan to work around Trump on issues they felt he wasn't handling properly.

'Kelly and Tillerson confided in me that when they resisted the president, they weren't being insubordinate, they were trying to save the country,' Haley wrote in an excerpt obtained by The Washington Post.

'It was their decisions, not the president's, that were in the best interests of America, they said. The president didn't know what he was doing.'

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Former UN Ambassador Nikki Haley claims that senior Trump advisers Rex Tillerson and John Kelly tried to recruit her to 'save the country' by undermining the president

In her forthcoming memoir, With All Due Respect, Haley describes a closed-door meeting where former White House Chief of Staff Kelly (left) and former Secretary of State Tillerson (right) asked her to help them work around Trump on issues they felt he wasn't handling well

Trump took to Twitter on Sunday evening to wish Haley luck with her book. He tweeted: '@NikkiHaley is out with a new book, 'With All Due Respect' this week. Make sure you order your copy today, or stop by one of her book tour stops to get a copy and say hello. Good luck Nikki!'

Haley described Tillerson as 'exhausting', and said the secretary of state told her that 'people would die' if Trump went unchecked.

She also claimed that Kelly was suspicious of her access to the Oval Office.

Haley expanded her account of the closed-door meeting with Tillerson and Kelly during an interview with CBS anchor Norah O'Donnell that aired Sunday.

'Instead of saying that to me, they should've been saying that to the president, not asking me to join them on their sidebar plan,' she said.

'It should've been: 'Go tell the president what your differences are, and quit if you don't like what he's doing.'

'But to undermine a president is really a very dangerous thing. And it goes against the Constitution, and it goes against what the American people want. And it was offensive.'

When asked about Haley's account, Kelly responded: 'If by resistance and stalling she means putting a staff process in place … to ensure the (president) knew all the pros and cons of what policy decision he might be contemplating so he could make an informed decision, then guilty as charged.'

Tillerson did return requests for comment.

Trump took to Twitter on Sunday evening to wish Haley luck with her book. He tweeted: '@NikkiHaley is out with a new book, 'With All Due Respect' this week. Make sure you order your copy today, or stop by one of her book tour stops to get a copy and say hello. Good luck Nikki!'

Haley has remained a fierce Trump supporter even after she left her post as US ambassador to the United Nations in October 2018. She is pictured with the president in September 2017

Haley also addressed the House impeachment inquiry against Trump during the CBS interview, likening it to a 'death penalty' and saying she does not think the president will be removed from office.

'You're going to impeach a president for asking for a favor that didn't happen and — and giving money and it wasn't withheld? I don't know what you would impeach him on,' she said.

'Impeachment is, like, the death penalty for a public official. When you look at the transcript, there's nothing in that transcript that warrants the death penalty for the president.'

House Democrats launched the inquiry in September amid the revelation that Trump may have threatened to withhold $400million in military aid to the Ukraine unless its president, Volodymyr Zelensky, opened an investigation into former Vice President Joe Biden.

Haley's new memoir, With All Due Respect, will be released on Tuesday

The White House has repeatedly branded the inquiry as a 'witch hunt' spearheaded by 'unhinged' Democrats.

Democratic lawmakers have said there is evidence that the president committed an abuse of power by trying to strong-arm the Ukraine into an investigation to hurt his rival and possible 2020 election opponent.

Haley dismissed the idea that there was a quid pro quo in Trump's dealings with Zelensky.

'The Ukrainians never did the investigation. And the president released the funds,' she said. 'I mean, when you look at those, there's just nothing impeachable there.

'And more than that, I think the biggest thing that bothers me is the American people should decide this. Why do we have a bunch of people in Congress making this decision?'

Haley also defended Trump regarding an inflammatory statement he made on Twitter over the summer, when he told four Democratic female members of Congress, three of whom were born in the US, to 'Go back and help fix the totally broken and crime infested places from which they came'.

The politician, who herself is the daughter of immigrants, admitted that Trump's words were 'not appropriate', before adding: 'But I also can appreciate where he was coming from, from the standpoint of, don't bash America over and over and over again and not do something to try and fix it.'

The CBS interview and forthcoming memoir mark Haley's first major public comments since she resigned as UN ambassador in October 2018.

The former South Carolina governor said she has no immediate plans to run for office, but that remains a possibility in the future.

'A year is a long time in politics. It really is a lifetime in politics. And so, I think what's best for me is take it a year at a time and see what happens,' she said.