LAS VEGAS • Mr Donald Trump hit back at forces within his party who may try to stop him from formally capturing the presidential nomination at the Republican National Convention, calling their reported plans "illegal" and urging a unified effort to win.
"First of all, it's meaningless. Second of all, it's illegal. Third of all, you can't do it," Mr Trump said at a rally at the Treasure Island casino on the Las Vegas Strip on Saturday.
Later in Phoenix, Arizona, while continuing a campaign swing through the west, Mr Trump said that talk of a convention challenge was being manufactured by the media, and that the Republican National Committee was behind him "100 per cent".
Tensions have flared regularly between Mr Trump and some establishment figures within the party since he became the presumptive nominee in late May.
The Washington Post reported last Friday that Trump critics hope to challenge him in Cleveland next month by making changes to rules governing the convention. "Dozens" of Republican delegates were said to be on board.
First of all, it's meaningless. Second of all, it's illegal. Third of all, you can't do it.
MR DONALD TRUMP
Should the efforts gain traction, decisions made by the rules committee before Cleveland could have a big impact on how things play out.
On Friday, the party named former Representative Enid Mickelsen from Utah to oversee the panel that is responsible for reviewing and modifying rules for the convention and the party's operations. Ms Mickelsen is seen as a potential ally of Mr Mitt Romney, the 2012 Republican presidential nominee, who now makes Utah his primary residence and who has been the leading anti-Trump forces within the party.
Mr Trump, in turn, has called Mr Romney "a choke artist" for losing in 2012, and Mr Paul Manafort, Mr Trump's convention manager, last week called the former Massachusetts governor a "coward".
"We get almost 14 million votes, we win 36, 37 states - others win none. None. Now people who got none are saying, 'Maybe we can get something at the convention,'" a fired-up Mr Trump said in Las Vegas. "It doesn't work that way, folks."
He said former Florida governor Jeb Bush, one of the more than a dozen Republicans vanquished during the party's primary elections, may be among those attempting to undermine him. "Jeb is working on the movement, just so you understand," he said in Las Vegas.
Bush spokesman Kristy Campbell responded on Twitter that "Donald Trump's unending obsession with @JebBush is really unhealthy".
Some Republicans are anxious about the impact on November's congressional races and other electoral contests of having Mr Trump as the party's standard-bearer, suggesting certain potential donors could hold back.
"You know, I'm an outsider and I won the primaries," Mr Trump, 70, said in an interview with NBC's Meet The Press. "We can win either way, but it would be nice if we stuck together."
In Las Vegas, he said he had raised US$12 million (S$16 million) to US$13 million for the party in the past two days alone, and that if Republicans "don't want to help out as much, I'll fund my own campaign".
Polling this week showed that Mr Trump's negative ratings, already high, spiked again after briefly tapering off in May.
An ABC News/Washington Post poll released last Wednesday found that 70 per cent of Americans view him unfavourably, up 10 points on the month.
Presumptive Democratic nominee Hillary Clinton's unfavourable rating also rose, to 55 per cent from 53 per cent.