A former long-time aide to Donald Trump who lost his position over racially charged Facebook posts switched sides Monday in the Republican presidential sweepstakes, saying he now backs Texas Sen. Ted Cruz.

Sam Nunberg told Politico's morning 'Playbook' newsletter that 'Donald Trump does not have a coherent political ideology – if anything, I would describe him as a Chris Christie Republican.'

In a phone interview with DailyMail.com, Nunberg summed up his disappointment with his former boss's recent foreign policy turns by saying that 'our electoral chances with him as the nominee are close to nil.'

'Ted Cruz is a Reagan conservative. I don't even know what Donald Trump is,' he concluded, saying Trump's recent pronouncements on global affairs put him in an isolationist class with 'Charles Lindbergh, Pat Buchanan and even George McGovern.'

'His foreign policy makes Hillary Clinton look like Winston Churchill,' an angry Nunberg complained, citing The Donald's recent pronouncements about NATO's obsolescence, a sudden reluctance to tear up the Obama administration's nuclear deal with Iran, and other policy positions in the Middle and Far East.

KEEP CALM AND TAKE REVENGE: Fired Donald Trump aide Sam Nunberg jumped off the Trump Train on Monday, saying he is now supporting Ted Cruz – seven months after he was canned for racially charged Facebook postings

TOP-TIER ENDORSER: Ted Cruz (left) now has among his backers a former staffer to Donald Trump (right) who was bounced from that campaign for writing a racist message on Facebook

'When you listen to him talk about trade, it's like listening to poetry,' Nunberg said. 'But on foreign policy, it all falls flat. He simply isn't interested in it.'

That, he predicted, would spell doom for Trump in a general election against Hillary Clinton, the Democratic former secretary of state.

'The rules of political gravity will apply in a two-person race. The Democrats are not going to sit around and wonder how to take him down. It could be disastrous.'

'You could even lose the House,' he said, imagining the impact on down-ticket congressional races.

Nunberg got the axe in August after a cryptic Facebook post was discovered dating back to 2007 in which he wrote: 'Meeting Rev. Sharpton today, no joke- he will tell him that his daughter is N---!'

He did not work for Trump at the time, but The Donald's campaign cut ties with Nunberg as a rift quickly widened between him and campaign manager Corey Lewandowski.

In the months that followed, Nunberg remained a steady Trump booster behind the scenes – keeping his name in the news by offering consistent praise for his old mentor and friend.

'I'm a supporter. I'm not on his payroll. Trust me,' Nunberg told DailyMail.com on February 27.

On Monday he insisted that he's also not on Cruz's payroll.

'No, not at all,' Nunberg said. 'I'm not going to have a job with them either.'

'I think that they're indifferent,' he said of the Cruz orbit. 'I'm not a surrogate for them, they're not a client of mine. I'm a supporter. I haven't heard from them about this. They had no idea at all.'

But there's a hint of karma in what could be Nunberg's final 15 minutes of fame – he says he's working outside electoral politics now.

The same personal Facebook page where Nunberg once dished tasteless dirt about Republican politicians included a cover photo depicting a skull with the slogan: 'Keep Calm and Take Revenge.'

THE NUNBERG FILES: Trump's one-time adviser left his Facebook wall unprotected, bringing a hailstorm of criticism and his swift exit from a position with the leading Republican presidential campaign

'His candidacy at first was an aspirational "movement" candidacy,' Nunberg recalled during a phone interview while he was walking down a noisy New York City street.

'Now it's turned into a grievance pitchfork novelty candidacy. And when I say that, I mean that it's all about Trump. It's a cult of identity. It's almost Obama-esque, like in 2008.'

The real estate tycoon 'had the potential to bring the party together. Instead he's torn it apart,' Nunberg said, 'He used to talk about a movement, that it's all about us. Now it's all about him. Now it's not about unity for trade or unity for jobs. It's unity for getting behind Donald Trump.'

The November election, in Nunberg's view, will be a bloodbath favoring Democratic candidates if Trump wins the GOP nomination.

'I believe there are more anti-Trump Republican voters who will not vote for Trump in the general, compared to Trump-only voters,' he said, forecasting anti-Trump forces voting with their feet.

Other Facebook posts that sealed Nunberg's fate with the Trump campaign last August included some that called President Barack Obama a 'Socialist Marxist Islamo Fascist Nazi Appeaser,' 'Farrakahn's Messiah,' and a 'Pan Arabist Marxist Muslim.'

Before Obama's first inauguration in 2009, Ted Cruz's newest endorser wrote that there were, 'still tickets available for the Hip Hop Inaugral [sic] Ball – G-D help us!'

He called Sen. John McCain an 'open border Republican' who is throwing the GOP 'down Taco Bell's toilet.'

And Nunberg's Facebook wall included attacks against Gov. Christie – calling him a 'fat slob who should register as a Democrat' and claiming the only thing Christie likes 'more than lasagna' is himself.

He told DailyMail.com on Monday that if would be unfair to cast him as a racist.

'I'm not David Duke or the KKK. This was seven or eight years ago,' he said. 'I was fired by Donald Trump on a Sunday and forgiven by Rev. Sharpton, quite graciously, on a Monday. I'm not some kind of leper walking around with a scarlet letter on my forehead.'

At the time the posts were discovered, Nunberg expressed bewilderment and said he didn't recall writing them.

'I am not adept at social media,' he told CNN on August 2. 'I have a long record of working with diverse people. And anything you are reporting on does not reflect anything on Mr. Trump or Mr. Trump's campaign.'

'I would also point out that all of these things were done before Mr. Trump's campaign, if I even did them – which I deny.'

He told Politico on Monday that he had jumped off the Trump train in February when he heard him 'telling Morning Joe "I am really good at this stuff" on foreign policy when he is not.'

'When did I decide that I could no longer support Trump? Last fall, when he did not have any idea of what the nuclear triad is in a debate,' Nunberg said. 'I was concerned, but I figured that he would bulk up on policy. He has not.'

But on February 27 during a conversation with DailyMail.com, Nunberg scoffed at the idea that Florida Sen. Marco Rubio, then engaged in a daily war of words with Trump, could beat him by turning 2016 'into a foreign policy election.'

'Come on!' he said then. 'Mr. Trump is qualified to be commander-in-chief.'

A Trump campaign spokeswoman declined to discuss Nunberg's change of position on Monday.

WAR OF WORDS: Nunberg's Facebook wall used the header graphic at right when his distasteful postings were discovered

Nunberg told Politico on Monday that the idea of a a floor fight in July to determine the Republican presidential nominee shouldn't be scary to GOP voters, seemingly joining the chorus of Cruz partisans whose strategic toolbox now consists of a plan to deny Trump the nomination on the first ballot by stopping him short of a 1,237-convention delegate majority.

'If an open convention was good enough for Lincoln, Eisenhower, Nixon and Ford, it is good enough even for the great Donald Trump,' Nunberg scolded.

'If Trump’s opponent had 1,236 delegates and he had 1, he would be demanding a brokered convention.'

But a month and a day ago, Nunberg warned of a conspiracy inside the Republican Party to deny Trump a victory he would win far and square.

He described the real estate tycoon then as 'the presumptive nominee. ... He's proven he's the front-runner, that he can win, that he's legitimate, and now he's getting endorsements from establishment-type politicians like Chris Christie.'

But 'if we get to April and May,' he said of a protracted primary fight, 'the longer it goes, Mr. Trump will be at a disadvantage because the party apparatus doesn't want him to be the nominee.'