AN EXPLOSIVE new book describes the depth of the dependence and “consuming obsession” between former prime minister Tony Abbott and his chief of staff Peta Credlin, which ultimately cost them both their jobs.

Senior members of the government told The Australian journalist Niki Savva, whose book Road to Ruin: How Tony Abbott and Peta Credlin Destroyed Their Own Government is out on Monday, that they tried to get Abbott to sack Credlin and avoid losing the leadership.

Savva writes that “Abbott lived in a bubble built for two”. There were even rumours that the duo were having an affair.

At one point, NSW Liberal MP Concetta Fierravanti-Wells confronted Abbott about the rumours.

“Politics is about perceptions,” she told him. “Rightly or wrongly, the perception is that you are sleeping with your chief of staff. That’s the perception, and you need to deal with it.

“I am here because I care about you, and I care about your family, and I feel I need to tell you the truth, the brutal truth. This is what your colleagues really think.”

Both Credlin, who is married to former Federal Director of the Liberal Party Brian Loughnane, and Abbott denied the affair.

But the book includes some extraordinary anecdotes which reveal the level of trust and intimacy between the pair.

One MP claims to have witnessed Ms Credlin using her fork to feed Abbott mouthfuls of food from her plate. After the meal “she put her head on his shoulder to complain about being tired”.

The MP who witnessed this strange behaviour in a Melbourne restaurant told Savva: “I have only ever done that with my partner or a date.”

One long-time Coalition staffer compared their relationship to that of King Edward III and American socialite Wallis Simpson, who were famously “slavishly dependent” on each other.

“This was not meant to imply an affair; it was meant to describe the depth of the dependence, the consuming obsession, and what Abbott was prepared to sacrifice for it,” Savva wrote.

Just the very insinuation that @TonyAbbottMHR was having an affair with #Credlin makes me want to throw up everywhere. #auspol — The Chronicles (@JamieRGonzalez) March 4, 2016

“Like King Edward VIII, who gave up his throne because he could not do the job without Wallis by his side, Abbott had convinced himself he could not do it without Credlin. Ultimately, it cost him the highest office in the land.”

In his analysis of the book, Herald Sun political commentator Laurie Oakes says Credlin believed she could not leave because Abbott was incapable of doing his job without her.

“She revealed this to a Liberal MP after the leadership spill motion that marked the beginning of the end for Abbott. And Abbott, in Savva’s view, agreed,” he wrote.

“The book quotes with approval the view of a senior government adviser that ‘he knew he wasn’t up to it, she knew he wasn’t up to it, so they both hunkered down’.”

Abbott’s colleagues became increasingly frustrated with his refusal to fire Credlin.

“Their motives were simple,” Savva wrote. “They wanted the government to be re-elected, yet they were convinced that will Abbott as leader they would get smashed.

“They could not find the means to separate the two people at the helm, held in bonds so tight that no one else could penetrate.

“They were not only destroying one another, they were destroying the government too.”

Oh god, what an awful thing for the other diners in the restaurant to experience!#Credlin feeding #Abbott #foodporn https://t.co/VahgDX3B0W — Lady Velvet Gloves (@Baxeybel) March 4, 2016

'I did not have sexual relations with Peta Lewinsky' - Tony Clinton #auspol #Abbott #Credlin — michael halliday777 (@michaelhallida4) March 4, 2016

Ms Fierravanti-Wells also confronted Credlin and asked her to resign.

She said: “One day, Tony will be sitting on a park bench in Manly feeding the pigeons, and he will blame you.”

The book’s release comes amid claims that Abbott is attempting to stage a comeback.

He will recontest his Sydney seat of Warringah and this week he headlined a Liberal fundraiser in Tasmania and again warned his party against making changes to the tax system, especially to negative gearing.

News.com.au has contacted Mr Abbott’s office for comment.

Read an exclusive extract of Niki Savva’s book in The Weekend Australian.