The Irish American politician Paul Ryan (46) was all set to take over as the key figure in the Republican Party at an age and time when the future seemed limitless.

A White House run down the road was certainly in the offing, and the fresh faced workout nut was exactly the kind of new and engaging face the GOP, the tired old party of Senators John McCain, Mitch McConnell, et al, needed.

But a funny thing happened on the way to the coronation. Out of nowhere bounded a brash bulldog who proceeded to lift his hind leg and show the Grand Old Party what he thought of it.

Donald Trump’s ascension to the Republican nomination ranks up there as one of the greatest political shocks of any American presidential election -- ever.

Just a year ago commentators openly laughed at the possibility, and most suspected he was running to pump up his reality TV brand.

Instead, he peered into the heart of the GOP and deciphered it was rotten at its core, full of useless leaders and old bromides staler than Brennan’s Irish sliced pan bread a week later.

Ryan knew that was so in his heart, but lacked the chutzpah of Trump to call it as it was. Instead he hummed and hawed and talked about party unity the way a chief lemming might discuss whether to march off a cliff or not.

Republicans are losers of five of the six last popular votes for president and suddenly adrift on a ship called Hopeless with a destination called Nowhere. Trump, not Ryan, was hailed as the man of the hour who could rescue the passengers from shipwreck.

But to a hammer everything else is a nail, and Trump soon set upon dismantling the old order like a bad real estate deal and replacing it with…what exactly?

Indeed, he could not distinguish the GOP race from the general election in a primary a campaign that was aimed at winning over the faithful departed who had lost faith in the Paladins of the GOP, but which was never fit for purpose for a general election. Trump, novice that he is, failed to spot the difference.

Trump has lost the plot, castigating Mexican judges and Muslim immigrants, articulating an apocalyptic America on the verge of ruin (in other words, the Fox News staple diet night after night) and revealing an egotistical mania that bordered on the manic. His first reaction after Orlando was to praise himself for predicting it. With a mass murder happening every couple of months, it was hardly a great feat of actuarial science.

The sky is falling is no way to win an election in America, and Trump has shown himself utterly out of his depth. Politics ain't beanbag, and a real estate developer learning on the job is bound to be a disaster.

Worse, folks like Ryan continue to indulge him even as he blackens the name of America abroad and creates a deeply upsetting portrait of a country at war with itself on the verge of being overrun by immigrants.

This should have been Ryan’s Joe McCarthy moment to ask Trump if he had no shame, and demand he step aside for a better candidate for the sake of the party of Lincoln.

Alas, all Ryan could offer were idle threats carrying the force of a wet noodle. GOPers don’t do reality apparently, not even when the polls show them ready to fall off the cliff.