And he claims that Trump 'has already given up' on winning election

He also supports the women who say that Trump sexually assaulted them

Schwartz he says he's given all recent Art of the Deal royalties to charity

He says Trump can't be trusted with nukes, and is 'narcissistic,' 'paranoid'

Donald Trump is under attack from a man he once trusted: Tony Schwartz, the co-author - or, as Schwartz has it, ghostwriter - of 'The Art of the Deal.'

Trump himself hired Schwartz to co-write the memoir-cum-business guide, released in 1987. But as Trump's approach to the White House began to pick up steam this year, Schwartz became more and more vocal in his opposition to the Republican.

Now he maintains a rolling Twitter commentary on Trump's affairs in which he derides the candidate as 'narcissistic' and 'paranoid,' and warns that if given access to America's nukes, he could cause Armageddon.

Regrets: Tony Schwartz (right) says he regrets co-writing 'The Art of the Deal' with Donald Trump, and has devoted the past few months to trying to demolish his presidential campaign

'Fragile': Schwartz regularly tweets on Trump's campaign, and describes him as 'fragile' and a liability if given America's nukes. He told The New York Times Trump could cause Armageddon

'Evidence': Schwartz claimed that what he saw as Trump's brittle attitude in the presidential debates as 'evidence' that he would be pressured into firing nukes by Putin and other foes

'Lipstick': Schwartz likened attempts to make Trump affable in 'The Art of the Deal' to 'putting lipstick on a pig' and says he now gives royalties from the book to charity

On Saturday Schwartz tweeted: 'Trump is totally willing to blow up the world to protect his fragile sense of self. Please God don't give this man the nuclear codes.'

And on Monday, just after Sunday's presidential debate ended, he wrote: 'What Trump has done tonight is evidence of exactly who he is: feeling threatened, he will do anything. And he will have the nuclear codes.'

Those comments echo remarks he made to The New Yorker in July: 'I genuinely believe that if Trump wins and gets the nuclear codes there is an excellent possibility it will lead to the end of civilization.'

Schwartz spent a year following the businessman around to write 'The Art of the Deal' and describes himself as the book's ghostwriter, something Trump denies.

A post on Schwartz's Twitter feed reads: 'I wrote the Art of the Deal. Donald Trump read it.'

He paints a picture of Trump as a brittle mental munchkin, unable to take criticism and prone to lashing out when he feels threatened.

'Trump narcissism bleeds into paranoia in the face of likely defeat,' Schwartz tweeted Sunday. 'Gotta blame someone. He blames everyone except himself.'

Ghost: Schwartz followed Trump (pictured left in 1988, one year after the book was released) around for a year to write the book. He says the Republican is completely unfit for presidency

'Paranoid': Trump is 'narcissistic' and 'paranoid' - and incapable of taking any kind of criticism, says Schwartz

A lifelong liberal who accepted $500,000 and half the royalties to co-write 'The Art of the Deal' over the course of a year, Schwartz has since said the book was putting 'lipstick on a pig' and claimed personal responsibility for making Trump popular.

'I feel a deep sense of remorse that I contributed to presenting Trump in a way that brought him wider attention and made him more appealing than he is,' he told The New Yorker.

He also admitted to lying in the book, saying he wrote book's opening - 'I don't do it for the money ... I do it to do it ... That's how I get my kicks,' - and that it was a complete fabrication.

'Of course he’s in it for the money,' he told The New Yorker. 'One of the most deep and basic needs he has is to prove that "I'm richer than you."'

'Nasty': Schwartz mocked Trump's 'nasty' behavior during presidential debates, saying that the more aggressive he is, the smaller Clinton has made him feel

His response to Trump's presidential campaign, he says, has been to donate the book's royalties to immigration charities - as well as to strongly criticize 'The Donald.'

That includes using his position as an 'insider' to identify supposed psychological clues to Trump's mindset on Twitter.

'Every time Hillary makes Trump feel small, he gets nasty, aggressive, repetitive,' Schwartz said during the last presidential debate.

'Snorts. Wanders more. Scowls more, he said. 'Watch him respond now.'

'Again: When Trump snorts, he is lying,' he added.

'Repetitive': Schwartz claims to be able to tell how Trump is feeling by his reactions, including 'scowling' and 'wandering' when under pressure

'Lying': 'When Trump snorts, he is lying,' Schwartz claimed

Schwartz also responded to Trump's recent implication that Clinton was on performance-enhancing drugs in the presidential debate.

During a rally in Portsmouth, New Hampshire, Saturday, Trump said: 'We should take a drug test, prior (to the debate).

''CauseI don’t know what’s going on with her, but at the beginning of her last debate, she was pumped up at the beginning, and at the end it was like, "Oh, take me down."

'She could barely reach her car. So I think we should take a drug test.'

In a Sunday tweet, Schwartz appeared to imply that Trump himself was on drugs.

'What's funny about Trump saying Clinton was on drugs at debate is that he was the one snorting, jacked up, pacing the stage,' he wrote. 'Projection?'

'Projection': Trump has claimed that Clinton was on performance-enhancing drugs. In this tweet, Schwartz appeared to imply that Trump was himself on an unknown substance

'Nauseating': Schwartz also supports the nine women who have come forward to say that Trump sexually abused or harassed them, and says Trump 'lies for a living'

And he has vociferously backed the nine women who have come forward in the past week accusing Trump of sexually assaulting and harassing them.

'Nuts to believe Trump didn't assault these women coming forward,' he tweeted Friday. 'They have 0 to gain and lots to lose. He lies for a living. Nauseating.'

In another Tweet from Sunday, Schwartz said: 'Imagine this: Trump alone in a room with your daughter. Trump as a role model for your son.'

Imagine: Schwartz believes that Trump is not a fit role model nor fit for President

But Schwartz, who is now founder and CEO of The Energy Project, which helps companies run sustainably, now believes the Trump campaign is all but over.

More importantly, he says Trump believes that too.

'I said earlier Trump would soon starting talking about rigged election. He did tonight in Wilkes Barre,' he tweeted on Tuesday.

'Means he has essentially given up.'