The rise of Donald Trump has shown America and the world that the GOP is no longer fit for purpose.

A once serious party has been successfully hijacked by white nationalists, wild-eyed conspiracy theorists, racists, anti-Semites, give-no-quarter demagogues and the alt-right.

This cabinet of horrors used to constitute the lunatic fringe. They used to know that they did too and they seethed with resentment over it, marinating in their own fury.

For most of our lifetimes they were the voices on the fringes. No longer. The Internet changed that. Breitbart changed that. Infowars changed that. And by inviting them onto primetime national airwaves, Fox News and Rupert Murdoch have changed that too.

Read more: Donald Trump’s various and vicious conspiracy theories

As late as five years ago these fringe voices were identified as the radical right. Now they are impulsively retweeted and quoted by their once-in-a-lifetime leader Donald Trump, even from the presidential debate stage.

Trump’s campaign nailed its colors to the mast when it named Breitbart News chairman Stephen Bannon as its CEO – the man who has overseen the transformation of the Breitbart website from a conservative gathering place to a town hall for the alt-right.

New @ABC News tracking poll: Share of registered Republicans likely to vote drops 7 points since mid-October: https://t.co/p9uMZLzoKK pic.twitter.com/EWSWS39Jxu

— ABC News (@ABC) October 24, 2016

Conservatives had already been scornfully calling the site Trumpbart, but even they didn't think that Trump himself would actually make Bannon CEO of his campaign, setting its tone and its terms of reference.

Constitutional conservatism was the view that dared not speak its name this campaign season, as the hordes of its strangely silent party leaders reminds us. Instead they fell like red maples to a chainsaw, afraid to speak in case they caught the ire of the vengeful Trumpbart hordes.

Trump didn’t distance himself from the enthusiastic endorsement of former Ku Klux Klan leader David Duke; he pointedly failed to condemn the hideous alt-right anti-Semitic attacks on journalists (images of gas chambers, prison bars and yellow stars were published, bullet holes were added to journalists' profile pictures). It’s as though we have been watching the rise of a Führer in the 1930’s rather than a president in 2016.

There is “something” wrong in American society that “only” Trump can “fix” is the phrase he likes to parrot. What that “something” is depends on whom he is speaking to, but the cast includes Muslims, Mexicans, the media, and “the African Americans,” all of who will be hearing from him if he ever becomes president, he assures us.

Trump campaign CEO Steve Bannon blasted Republicans for complaining about unfair media coverage in 2012 https://t.co/XvVHWJyKIV pic.twitter.com/DzEJzBnIVf

— BuzzFeed News (@BuzzFeedNews) October 18, 2016

But the thing is he won’t ever become president. His cabinet of horrors is not what America is about. In fact it is what every generation of Americans has passionately resisted and very shortly he will get that memo.

Britain has a lesson to teach us about all this. The destructive rise of the fringe right within conservatism there has resulted in a damaging piece of political theatre that has injured its standing in Europe and the world.

More to the point the damage has been internal too. Brexit is not what the parties that signed the Good Friday Agreement agreed to. In fact, it makes a mockery of their efforts. It would be tragic if we allow our resurgent far right to similarly damage our standing on the world stage.

Meanwhile Bannon and Trump are now the face of the GOP brand, its standard bearers. They don’t practice politics – they wage war. They have ridden roughshod over a once great party. They have silenced or marginalized its most ardent adherents, but their destination isn’t the future, it’s a precipice.

Four years won’t be enough time to undo the damage they have already wrought on the Republican Party. Four years will not be enough time to defuse the national destruction of the Trump era. They are looking at sixteen years in the wilderness for a reason.

It is time for constitutional conservatives to create an entirely new brand.

Donald Trump on stage at the Republican National Convention.Getty