Donald Trump insisted there was "great unity in my campaign" on Wednesday although there were several indications the Republican Party was turning against its nominee.

Senior Republican figures were growing increasingly concerned about Mr Trump's behaviour following his criticism of the family of a dead Muslim American soldier and his refusal to back the re-election campaign of Paul Ryan, the house speaker.

Frustration at Mr Trump's divisive tactics and insulting comments reached new heights on Wednesday, with several extraordinary developments:

'Intervention plot'

Senior Republicans including Reince Priebus, chairman of the GOP, Rudy Giuliani, former New York City mayor, and Newt Gingrich, the former house speaker, were reportedly considering an "intervention" meeting with Mr Trump.

They hoped to talk Mr Trump into "a dramatic reset of his campaign", NBC reported. “A new level of panic hit the street,” Scott Reed, chief strategist for the US Chamber of Commerce, told The Washington Post. “It’s time for a serious reset.”

Mr Gingrich, a Trump ally, said his friend currently stood no chance of beating Hillary Clinton in November. “The current race is which of these two is the more unacceptable, because right now neither of them is acceptable.