Tony Abbott has declared himself an “outsider” like US President Donald Trump and suggested the Turnbull government is guilty of “economic irresponsibility” and a “moral failing” over debt and spending.

In a new book analysing his legacy, Mr Abbott offers an afterword in which he explains his political philosophy, defends his time as Liberal Party leader and lays out his future vision for the conservative movement.

Mr Abbott writes that the “run of massive deficits” that began in 2008 are “continuing to this day with no credible end in sight”.

In an implicit criticism of the Turnbull government, which observers have said laid down a “tax and spend” budget this year, Mr Abbott describes the situation as “not just economic irresponsibility but a moral failing too”.

Elsewhere, the former PM draws a comparison between the election of Mr Trump last year and his own triumph in 2013.

“In an era of thwarted expectations, it’s easier for outsiders than for insiders to win elections,” he writes in the book Abbott’s Right, published on Monday.

“This helped me in 2013. The insider versus outsider dynamic was clearly at work in the Brexit referendum result. It certainly helped Donald Trump in the 2016 United States election.”

Mr Abbott, a former Rhodes scholar, has been in Parliament as a Liberal MP for 23 years.

His essay is published in a book analysing his legacy by conservative author and lawyer Damien Freeman.

The former PM also appears to respond to a major speech given by Mr Turnbull in July, where he argued that Liberal Party founder Sir Robert Menzies “went to great pains not to call his new centre right party a conservative party”.

Mr Turnbull cited the former prime minister’s famous quote: “We took the name ‘Liberal’ because we were determined to be a progressive party, willing to make experiments, in no sense reactionary but believing in the individual, his right and his enterprise, and rejecting the socialist panacea.”

But Mr Abbott writes that the passage in question is “sometimes used to make conservatives look like interlopers in the party he formed”.

He adds: “Much less familiar is Menzies’s despairing 1974 observation … about the party’s Victorian state executive: ‘dominated by what they now call ‘Liberals with a small l’ that is to say Liberals who believe in nothing but who still believe in anything if they think it worth a few votes. The whole thing is tragic’.”

Some conservatives have expressed frustration with the direction of the government under Mr Turnbull, who is a moderate.

The new essay comes as Mr Abbott positions himself prominently ahead of the same-sex marriage postal vote, which he has described as a vote on “political correctness”.

He also made headlines this week after finally admitting he had missed parliamentary votes on the former Labor government’s economic stimulus bill in 2009 because he was drunk.

Former Labor treasurer Wayne Swan, who was forced to withdraw his suggestion in Parliament that Mr Abbott had been drunk, said the then-Liberal frontbencher “slept through votes which were to save Australia from recession”.

“His priority was himself not the Australian people or their jobs,” Mr Swan said.

Mr Swan said he did not know why the former PM had finally admitted the truth.

“Perhaps he has completely utterly and completely lost the plot. It’s hard to know,” he said.