What are 'New York values'?
Perhaps we should call it the Frank Sinatra doctrine - the idea, enunciated nightly in karaoke bars the world over, that if you can make it in New York, you can make it anywhere. But is that true of presidential politics?
Texas Senator Ted Cruz clearly believes he is on to something in citing Donald Trump's "New York values" as a potential disqualifier for the Republican presidential nomination.
In rebuttal to Trump's claims that Cruz is dangerously Canadian - he was born in Calgary, but his mother is from Delaware, which makes him constitutionally eligible to be president - the Texan has hit back with something potentially as damaging - that Trump is a New Yorker.
This attack line not only equates Gotham with Sodom and Gomorrah. More wounding is the insinuation that the Manhattan billionaire is not a true conservative.
What precisely does Cruz mean by "New York values"? In the latest Republican debate, as he repeatedly duelled with Trump, he explained.
"Everyone understands the values in New York City are socially liberal, pro-abortion, pro-gay marriage and focus around money and the media."
Then he cited an interview that Trump conducted years ago with the late Tim Russert of NBC News, which touched on his moderate views.
"Look, I'm from New York. That's what we believe in New York," Mr Trump said at the time.
To prosper in the Big Apple, Republican politicians ordinarily need to adopt moderate policies, especially on social issues like abortion, which make them unviable as Republicans nationally. Just ask Rudy Giuliani, the highly successful mayor of New York City, who floundered as a presidential candidate when he sought the Republican nomination in 2008.
Giuliani was a surprisingly lacklustre campaigner, but the fact that he hailed from New York, and thus from the moderate wing of the party, handicapped him from the outset. Even his reputation as "America's Mayor", the hero of the hour in the aftermath of the attacks of 11 September, could not save him.
Nelson Rockefeller, the highly successful governor of New York and a scion of the famed banking dynasty, was also damaged by New York values. A divorcee, he married his one-time secretary "Happy," which derailed his candidacy in 1964. America simply was not ready for a divorcee to become president, even though Rockefeller was eminently qualified to do the job.
That year saw the great emblematic battle in the Republican Party between the forces of moderation, represented by Rockefeller, and the newly insurgent right, with Senator Barry Goldwater of Arizona as its figurehead.
The triumph of Goldwater, a maverick who fiercely opposed civil rights reforms backed by moderates in his party, marked a watershed moment in GOP politics. The party's centre of gravity shifted from Wall Street to Dixie and the Sunbelt.
In the election, Goldwater was buried in a Lyndon Johnson landslide in the presidential election. In that crushing defeat, however, the seeds of future victories were sown - what became known as the southern strategy, which was aimed at harnessing the support of white voters worried by social change and black advance.
From the late 1960s to the early 90s, when the Republicans won all but one presidential election, the party benefited from a brand of conservatism that owed much more to Goldwater than Rockefeller.
It is also worth remembering that the Empire State has not produced a president since Franklin Delano Roosevelt and he, of course, was a Democrat.
So will Trump's Manhattan connections hamper him? The polls suggest not. First of all, he has never held office in New York, and therefore never needed to govern as a moderate Republican. He also has a David Bowie-like gift for re-invention, which has enabled him to brush off embarrassing evidence of past moderation, like his friendship with the Clintons and that interview with Tim Russert.
From the moment he launched his candidacy, moreover, with that outspoken attack on Mexican immigrants, he has not only sought to demonstrate that he is a true conservative but also to demonstrate that he is the most conservative. Not even Ted Cruz has backed his proposal for a temporary ban on Muslims entering America, the type of stance previously associated with far-right hate groups.
Besides, with Donald J Trump, the normal laws of political gravity do not seem to apply.
So perhaps he should start playing New York, New York at his rallies, as Ted Cruz has suggested.
And perhaps he will be able to upend recent political history and demonstrate that a Republican from the Big Apple can indeed become the party's top banana.