Donald Trump has tried to shift attention away from the perceived disarray in his campaign and in the Republican Party by dubbing Hillary Clinton the “founder of Isis”.

The New York mogul made the incendiary remarks at a rally in Daytona Beach, Florida, after days of campaign pandemonium triggered first by his feud with the father of a Muslim-American soldier slain in Iraq and then his refusal to back the re-election of House speaker Paul Ryan.

In Florida, which is likely to emerge as one of just a few swing states that will determine who wins the White House in November, Mr Trump appeared to be following the advice of some in his party and concentrate his fire exclusively on his opponent.

The Republican nominee offered a list of things that had gone awry in places like the Middle East and Libya, asserting that the fault on each occasion lay with Ms Clinton who served as Secretary of State in Mr Obama’s first term. Among the disasters, he says, was the rise of Isis.

“It was Hillary Clinton,” Mr Trump declared flatly. “She should get an award from Isis as the founder of Isis.” The assertion just came a few days after he called his Democratic foe “the devil” in an interview with Fox News.

He also directly addressed the ruckus created by his assertion to The Washington Post on Tuesday that he was not inclined to support the re-election bid of Mr Ryan or that of Senator John McCain, whose path back to Capitol Hill this November is looking particularly rocky. It caused a tempest of Republican handwringing and claims the party was irreversibly split.

It also prompted a firestorm of speculation that somehow Mr Trump would be forced to abandon the race for president and the job of finding a replacement would be taken up by the Republican National Committee chairman, Reince Priebus. The latter, according to numerous reports, was livid with Mr Trump for refusing to back the two top Republicans.

“The campaign is doing really well,” Mr Trump insisted as he started the rally in Daytona Beach, a city on the Atlantic side of Florida that is part of a key electoral corridor stretching west to Orlando and eventually to Tampa on the Gulf of Mexico.

“I would say right now it's the best we've been in terms of being united,” he went on, though on what grounds he could possibly claim such a thing was unclear. The party, “has never been more united,” he attempted again.

As well as going after Ms Clinton directly, Mr Trump also assailed President Barack Obama. “We have a president who is frankly incompetent,” he said. “We’ve been humiliated by President Obama and his policies.” He cited Libya as an area where US policy that had gone especially wrong. That, however, he blamed more on Ms Clinton.

“Libya! Look at that mess and that was Clinton telling Obama what to do…he’d love to have a do-over, I can tell you.”

Among Republicans who were urging Mr Trump to change direction, particularly after his protracted back-and-forth with the father of the slain soldier who had challenged him and his past rhetoric about Muslims from the stage of the Democratic Convention, was Newt Gingrich, who has otherwise been one of his main backers.

“The current race is which of these two is the more unacceptable, because right now neither of them is acceptable,” the former House speaker said in a telephone interview on Wednesday with The Washington Post. “Trump is helping her to win by proving he is more unacceptable than she is.”

Mr Gingrich went on: “Anybody who is horrified by Hillary should hope that Trump will take a deep breath and learn some new skills. He cannot win the presidency operating the way he is now. She can’t be bad enough to elect him if he’s determined to make this many mistakes.”

In contrast to his unwillingness to support Senator McCain or Mr Ryan, the nominee used his visit to Florida to endorse Senator Marco Rubio for re-election, ignoring the old rivalry between them. Mr Rubio was among the last left standing trying to block Mr Trump’s path to the nomination during the primary season. He was regularly ridiculed by him as “Little Marco”.