The Republican party in the United States has backed itself down a populist dead end. For months, Donald Trump has confounded and wrong-footed his opponents in the race to be declared the Republican nominee for president by deploying a potent mix of bombast, abuse and outright falsehoods. On Tuesday, Ted Cruz, the last of Mr Trump's credible opponents, quit the contest. Mr Trump's likely nomination leaves the Republican party in peril – and has frightening consequences for the US and indeed the world should he go on to prevail in the November election.

In recent days, Mr Cruz made plain what he really thought of Mr Trump, a man he branded a "pathological liar" and "narcissist". This might be dismissed as the complaints of a sore loser, except that it so thoroughly captures Mr Trump's flawed character. Mr Trump looks set to be the first Republican nominee for president since Dwight Eisenhower who has not previously served in an elected position. That's not a flattering comparison to the memory of General Eisenhower.

Donald Trump's likely nomination leaves the Republican party in peril. Credit:Andrew Harrer

Yet many establishment Republicans are now performing the political equivalent of a contortionist act, seeking to reconcile their well-canvassed antipathy towards Mr Trump with the realisation he has secured enough delegates to be presumed the party's nominee. Republican chairman Reince Priebus said the party needed to "unite and focus on defeating Hillary Clinton." Such hypocrisy is breathtaking, but the damage entirely self-inflicted.

For many years now, Republicans have mistakenly encouraged voters to believe complex social and economic challenges can be solved by an ideologically derived slogan. George W. Bush encapsulated this "I don't do nuance" logic and Mr Trump has simply pushed the tactic to the extremes. He revels in the politics of division, having infamously questioned Barack Obama's place of birth and ridiculed Muslims, Hispanics, blacks, women and the disabled.