Donald Trump has branded Hillary Clinton an “enabler” of her husband's affairs by destroying the lives of his mistresses, offering a foretaste of how he will take on his general election opponent and attempt to undermine her appeal to women voters.

During rallies on Friday, the presumptive Republican nominee delivered his strongest attacks yet on the former first lady after she criticised his stance on women's issues.

His ferocious tactics will do nothing to reassure senior Republican figures who fear the unpredictable billionaire will hand the White House to the Democrats in November's election or those who fear an even worse outcome: that he could actually win.