US Election 2016: Donald Trump claims there will be 'riots' if Republican elders challenge his presidential nomination

Tycoon issues stark warning to GOP grandees weighing up their options – including an arcane convention allowing them to parachute in another nominee

Republican presidential front-runner Donald Trump on bullish form as he addresses supporters at a primary election night event at his Mar-a-Lago Club in Palm Beach, Florida, (AP)

Flushed with success after more primary wins, Donald Trump has predicted “riots” if he goes to the Republican convention with the greatest number – but not a simple majority – of pledged delegates and an attempt is made to deny him the party’s presidential nomination.

While both Mr Trump and Democrat Hillary Clinton went significant distances in voting across five major states on Tuesday to consolidate their front-runner positions in each party’s contests, the Republican outlook was one of possibly even greater turbulence as chatter grew of a contested convention in Cleveland.

The New York billionaire is now closer to reaching the 1,237 delegates needed for the simple majority needed to lock up the nomination, following wins on Tuesday in Florida, Illinois and North Carolina. Senator Marco Rubio, after a drubbing in Florida – his own state – dropped out, making it a three-way contest with Senator Ted Cruz of Texas and Governor John Kasich of Ohio.

But securing a clean majority becomes more difficult for Mr Trump after his failure to pocket the 66 delegates offered by Ohio – that winner-takes-all contest was won by Mr Kasich. That leaves the door ajar for party elders to manipulate the arcane convention rules to block his path and potentially draft a different nominee – possibly not someone actually competing in the primaries.

As if the race wasn’t volatile enough, Mr Trump injected a warning of violence if his claim on the nomination were to be challenged at the convention. “I don’t think you can say that we don’t get it automatically. I think you’d have riots,” he told CNN. “I’m representing many, many millions of people.”

In response, the Republican party tried to play down Mr Trump’s comments. “First of all, I assume he is speaking figuratively. If we go into a convention, whoever gets 1,237 delegates becomes the nominee. It’s plain and simple,” Republican National Committee spokesman Sean Spicer told CNN.

In comments likely to raise more concern in the Republican establishment about Mr Trump’s temperament, he also said he was for the most part his own foreign affairs adviser. “I’m speaking with myself, number one, because I have a very good brain,” he told MSNBC’s Morning Joe show. “I know what I’m doing. My primary consultant is myself.”

The convention was not the only source of Mr Trump’s ire. In pugnacious form, he also declared that he would skip a Republican debate scheduled for next Monday by Fox News, promising to deliver a speech instead to the influential pro-Israel advocacy group Aipac. “How many times can the same people ask you the same questions?” he asked. “I won’t be there.” The event is set to be cancelled in its entirety.

At Mar-A-Lago, his palatial beach club in Palm Beach, Mr Trump again appealed to the Republican Party to acknowledge his success in fuelling sometimes record turn-out levels in the states that have already voted and unite behind him. “Something is happening” inside the party, he told a lavish ballroom of guests, mostly members of the club, and it was being noticed “all over the world”.

But Mr Cruz and Mr Kasich will not want to see that outcome. With Mr Rubio, briefly the great hope of the stop-Trump movement, now gone, a scramble will begin to attract his pledged delegates and his supporters in the states that have yet to vote. The stakes are especially high for Senator Cruz, who remains the only credible rival in the delegate count. He and Mr Trump were neck-and-neck in Missouri primary, which after Tuesday’s vote remained too close to call.

But Mr Cruz, whose base is evangelical Christians, faces a more complicated task, thanks to a commitment by Mr Kasich to stay in the race to the end, even though his own Ohio is the only state in which he has prevailed so far. With no chance now of reaching a delegate majority himself, Mr Kasich sees a brokered convention as his sole means of winning the nomination.

Blocking Mr Trump’s path is not his rationale for carrying on, Mr Kasich, the last establishment candidate running, asserted, while admitting his Ohio victory may have that effect. “I’m out there running to be President. I’m not out to stop Donald Trump or anybody else,” he said. “By winning yesterday in Ohio, I’ve dealt him a very big blow to being able to have the number of delegates.”

The deep schisms now wracking the Republican Party extend to whether a brokered convention is feasible or even wise. “There is nobody to broker a convention,” Haley Barbour, a former chairman of the Republican National Committee, told Yahoo News. “There’s not some group of wise men in a back room.”

Another influential voice, Rush Limbaugh, the conservative radio talk show host, warned his listeners that the party was preparing to use a contested convention to draft former Florida Governor Jeb Bush as a replacement nominee, never mind that his poor showings forced him out of the primary contests. Another name in the ether is Paul Ryan, the House speaker and the vice-presidential candidate last time around. But a spokesperson for Mr Ryan said he would “not accept a nomination”.

That he can still catch up with Mr Trump remains the hope of Mr Cruz, who is fully aware that a brokered convention would be unlikely to help him either.

“There are many in the Washington establishment who are having fevered dreams about a brokered convention, about a deadlocked convention where they parachute in an establishment candidate,” he told CNN. “I think that would be a disaster. The people would quite rightly revolt.”