His path to the nomination wide open, Donald Trump faces mutiny in the Republican ranks

Trump acknowledges he will need outside money to fight Clinton in general election

Donald Trump is the last man standing for Republican nod

His swift march from fringe curiosity to presidential nominee all but over, Donald Trump was confronting dangerous new challenges as the Republican Party he aspires to lead teetered on civil war and questions emerged about how he will fund his campaign going forward.

Mr Trump’s path to the Republican crown was abruptly cleared of all obstacles when, after being soundly defeated in the Indiana primary, Senator Ted Cruz abandoned his campaign late on Tuesday and Governor John Kasich of Ohio signaled his intention on Wednesday also to drop out.

While the hierarchy of the party called for a rallying of support behind Mr Trump, rebellion simmered both in the rank and file of the party and also among some of its more prominent figures. “If we nominate Trump, we will get destroyed.......and we will deserve it,” Senator Lindsey Graham of South Carolina, who was among the original 17 Republicans runners.

Mark Salter, a strategist for John McCain on his 2008 White House run said he would vote for Hillary Clinton, the likely Democrat nominee, before Mr Trump calling him “unfit for office,” and “temperamentally and morally, a narcissistic bigot”. Social media was littered with once die-hard Republicans setting fire to their Republican voter registration cards protesting Mr Trump.

For many who belonged to the #NeverTrump movement, the day of reckoning is here. He has not been stopped. Can they, many of them lifelong Republican operatives or donors, swallow their distaste for him? Steve Schmidt, who was Mr McCain’s manager, predicted that “a substantial amount of Republican officials who have worked in Republican administrations, especially on issues of defense and national security, will endorse Hillary Clinton.”

It is the scenario that many had feared, a Trump candidacy threatening to tear the Republican Party, also known as the GOP, apart. “Dearly Beloved, we are gathered here today to mourn the GOP, a once-great political party killed by epidemic of Trump,” said the Daily News front page in New York with a picture of an elephant, the GOP’s mascot, climbing into a coffin.

It is unclear what influence party leaders can have. “Look, we’re here. We’re going to get behind the presumptive nominee,” Reince Priebus, the chairman of the Republican National Committee, attempted before adding weakly: “Something new is probably good for our party.”

Whilst he would benefit from party unity, Mr Trump will not beg for it. “I am confident I can unite much of the party,” he told NBC, before adding: “Those people can go away and maybe come back in eight years after we served two terms. Honestly, there are some people I really don't want.”

One possible golden straw was a statement from Mica Mosbacher, the widow of Howard Mosbacher, who was in the George H. W. Bush cabinet, calling “fellow conservatives to unite and support our new nominee Trump”. Ms Mosbacher had previously been a key member of the Cruz campaign’s finance team.

The Trump campaign will be looking for other endorsements in the coming days from Republican stalwarts. Although even that necessity was downplayed by Corey Lewandowski, the campaign manager, on Tuesday night. “Of course, we will welcome endorsements of Trump from anyone who wants to endorse Mr Trump,” he told The Independent. “But we have been endorsed by 10 million voters and that’s what matters.”

Ed Rollins, an iconic figure in the party who was Ronald Reagan's 1984 campaign manager, declared he had joined a super PAC supporting Mr Trump, pledging to help raise money for the billionaire to counter the cash advantage he predicted Ms Clinton would have. “They're licking their chops,“ Mr Rollins says of Ms Clinton's team. ”They think they're going to win this thing.“

Mr Trump meanwhile acknowledged that he may be obliged to start taking more money from outside donors. He has spent about $44 million of his own fortune getting to this point, but a general election campaign could cost upwards of $1 billion. That risks damaging his carefully cultivated image of being a self-funded candidate, however.

“I do love self-funding,“ he said yesterday, but acknowledged there are limits even to his wealth. ”Do I want to sell a couple of buildings? I don't really want to do that,” he added.

The rise of Mr Trump threatened also to scramble the Republican strategy for keeping control of the US Senate in November. The majority leader, Senator Mitch McConnell, had previously indicated that if Mr Trump were the nominee he would not object if senators running for re-election disowned him. Some Republicans seeking re-election to the House of Representatives may also be tempted to do the same.

There were also signs meanwhile of second thoughts among some senior Republicans about refusing to hold hearings to confirm President Barack Obama’s choice for an empty seat on the US Supreme Court, Merrick Garland, for fear that Mr Trump may easily be defeated in November by Ms Clinton who may then nominate someone still further to the left.