In conceding, Cruz made no mention of the victorious Trump, who told a celebration at his Trump Tower in New York: "We're going after Hillary Clinton - she'll not be a great president. She'll not be a good president. She will be a poor president." Donald Trump's campaign has used songs by The Rolling Stones several times. Credit:AP Seemingly telegraphing plans for a highly personal campaign that would focus on jobs, the so-called Rust Belt states and Clinton family character and values, Trump declared almost in his first breath: "She does not understand trade. Her husband signed, perhaps, in the history of the world, the single worst trade deal ever done. It's called NAFTA. "We're going to bring back our jobs and we're going to keep our jobs. Let me tell you, the miners in Pennsylvania and West Virginia are going to start to work again. You're going to be proud again to be miners." In a rare acknowledgement of an opponent, albeit in defeat, Trump said of Cruz: "... he's one hell of a competitor. He's a tough, smart guy. And he's got an amazing future. I want to congratulate Ted. I know how tough it is. It's tough ... "

Continuing a recent and stunning winning streak, Trump seemed assured of at least 50 per cent of the vote in Indiana, while Cruz was trailing badly with a vote tally in the mid-30s. Donald Trump is the clear Republican front runner. Credit:Bloomberg In the Democrat race, Vermont senator Bernie Sanders won an upset victory, slowing Hillary Clinton's progress to the nomination and giving his campaign a much-needed boost as it enters its final stage. Based on vote counts and exit polls, Sanders was projected the winner by multiple television networks. Donald Trump waves as he leaves following a campaign event in South Bend, Indiana. Credit:Bloomberg

But despite his good showing in Indiana, Sanders is unlikely to alter the mathematical fact of the Democrat race - Clinton is and will remain the presumptive nominee. He has given no indication he'll drop out of the race before the final Democratic primaries in June. The punditry had assured Americans that Indiana was a pragmatic Midwestern haven in which political good sense would probably prevail - which was to say that Cruz might stop Trump in his tracks. But after six decisive primary wins, the Trump surge continued. Donald Trump greets attendees during a campaign event at Century Centre in South Bend, Indiana. Credit:Bloomberg A tweet by Republican National Committee chairman Reince Priebus, acknowledging that Trump was now the "presumptive nominee", seemed to confirm that the last stuffing had been knocked from the Stop Trump movement - a GOP establishment effort that always was too little, too late. In victory, Trump immediately appealed for the party to close ranks: "We want to bring unity to the Republican Party. We have to bring unity."

Attendees watch a television as primary results are discussed during an election night event for Senator Ted Cruz in Indianapolis, Indiana. Credit:Bloomberg And of the nation he said ahead of what is expected to be a bitter and brutal campaign: "We're going to love each other, we're going to cherish each other, we're going to take care of each other, and we're going to have great economic development." In that, the upshot was that at a point in the political cycle when the GOP is at its most ideologically conservative, it will ask Americans to vote for a candidate who speaks well of Planned Parenthood; is against trade deals and is opposed to cuts in Social Security and other entitlement programs; a guy who had donated to both sides of politics and who had the Clintons as guests at his 2005 wedding to Melania. A worker for former Republican presidential candidate Senator Ted Cruz removes the campaign sign from the podium following a primary night campaign event in Indianapolis. Credit:AP But a novice in the grunt and grind of political campaigning, Trump successfully pressed three hot buttons to electrify GOP voters - migration and borders; the loss of jobs in trade deals; and a rejection of the neo-con foreign policies of the Bush years.

Cruz's final gasp was his reliance on an extensive network of social and religious conservatives in Indiana - "without it, [Indiana] is a Trump state - it's a very strong base that is used to being mobilised", a hopeful local GOP official told reporters. Irony abounded in the results. Cruz claimed the backing of God, and lost; Trump boasted the support of convicted rapist and former boxing champ Mike Tyson, and he won. That conservative network that Cruz relied on can't be all it was cracked up to be. In what might have been the last mutual headbutt between Trump and Cruz on the campaign trail, Trump used a phone interview with Fox News to talk up an absurd and discredited tabloid report that Cruz's father had been photographed handing out pro-Fidel Castro leaflets with Lee Harvey Oswald, shortly before the latter assassinated President John F. Kennedy. Enraged and frustrated, Cruz branded Trump a "pathological liar", "a narcissist" and "a philanderer". "The country is depending on Indiana," Cruz warned later. "If Indiana does not act, this country could well plunge into the abyss ... We are not a proud, boastful, self-centred, mean-spirited, hateful, bullying nation."

Responding on Twitter, Trump tweeted: "Wow, Lyin' Ted Cruz really went wacko today. Made all sorts of crazy charges. Can't function under pressure - not very presidential. Sad!" In truth, the Cruz campaign peaked early in March. As measured by Gallup, the graph of what pollsters call net favourable ratings, the difference between candidates' "favourable" and "unfavourable" scores crossed dramatically - Cruz had been riding high, then his line began to tangle in that of the ascendant Trump; and in mid-April, the Trump line reached for the heavens and that for Cruz went to hell. Fifty-seven convention delegates were up for grabs in Indiana - 30 to the statewide winner and the remainder distributed to the winner in each of Indiana's nine congressional districts and, all up, Trump won at least 45 of them, according to The New York Times. That would push Trump through the 1000-delegate barrier and well within reach of the 1237 delegates needed to make the nominations his before the GOP convention in July – and with 482 delegates available in the remaining primaries, Trump is assured of winning significantly more than the 236 delegates he still needs.

Even before the results were in, Trump was itching to go after Clinton - he told a Monday rally: "I'd like to get onto Hillary - we've beaten all these [Republican] folks." There was poetic justice in Cruz's demise. Net favourable ratings for Cruz and Trump Credit:Gallup When former GOP speaker John Boehner, Cruz's nominal GOP ally, denounced Cruz last week as "Lucifer in the flesh" and then doubled down, throwing in that the Texas senator was a "miserable son of a bitch", it was clear Boehner's gripe was more than some mild irritation. Wind the clock back to 2014, when the GOP was riding high - in the midterm elections, it had won its biggest House of Representatives majority since 1928; it had a Senate majority for the first time in eight years; and it controlled 31 state governors' offices. It ought to have been a party poised for greatness.

In The Wall Street Journal, columnist Bret Stephens gets to the cause of Boehner's distress: "Instead, Mr Cruz used the moment to attempt a party coup by treating every tactical or parliamentary difference of opinion as a test of ideological purity. The party turned on its own leaders, like the much-vilified Mr Boehner. Then it turned on its [classically] liberal ideas, like free trade and sensible immigration policy. "Mr Cruz's trashing of his fellow Republicans hastened the arrival of the ultimate party crasher [Trump]. Arsonists who set fire to their neighbourhood run the risk of burning down their own house." But just because Cruz was the author of his own demise, it doesn't follow that Trump has been the architect of his own stunning success. He just happened to be a lucky bunny, hanging from an arc of political history, saying "me, me, me", as GOP voters gave up on their party. In the 1980s, the Republican Party won a new lease on life when the so-called Reagan Democrats defected to the GOP - in the main, they were white, blue-collar and Southern or rural.

Writing in The Washington Post, Eugene Robinson explains that traditional Republican orthodoxy would go only so far in keeping them in the GOP fold - small government, low tax, tight money, deregulation, free trade and lesser entitlements. "But most working-class Republicans are, get ready for it, working class," he writes. They are more Sam's Club than country club. "They don't own the business, they earn wages or a salary; and trickle-down economics has not been kind to them. Their incomes have been stagnant for a good 20 years, they have seen manufacturing jobs move overseas and job security vanish, they have less in retirement savings and home equity than they had hoped and they see their young adult children struggling to get a start in life." Trump has uttered words that sound like policies that scratch at those sores, without saying how he'll cure them. And the painkiller he offers is to play on voter fears, casting Hispanics and Muslims as the enemy; and the Republican establishment that might have addressed their ills as the riggers of a corrupt system that might have kept a good man down.

Robinson writes: "But it would be wrong - and for the Republican Party, suicidal - to ignore the fact that [Trump] is doing more than merely rousing the rabble. [He] is filling a vacuum left by years of inattention to voters who have been patronised and taken for granted." How do they go forward, this party and this candidate, who punches from both left and right with little regard for what the GOP holds as core policies? Will Trump's enthusiasm lift the Republican Party, or will the despondency of the GOP establishment sink Trump? Polling, particularly a new Florida poll suggesting that Democratic presumptive nominee Hillary Clinton would defeat Trump by 13 points in a general election face-off, is being used to delineate likely paths to the White House - and candidate Clinton's is so much easier than Trump's. In the event that Trump loses and he gets the blame, the Republican Party will have missed the point. As Indiana headed to the polls, The Washington Post editorialised on the failure by glaze-eyed GOP pooh-bahs to assert themselves: "Who knows why Republican politicians equivocate about the most repugnant political phenomenon in recent American history – opportunism? Cluelessness? A sincere wish to influence the process for the better?

"Any of those, or a combination, would be preferable to a fourth alternative: actual approval of what Mr Trump stands for - though plainly there is some of that too." Follow FairfaxForeign on Twitter Follow Fairfax Foreign on Facebook