Donald Trump soared into a poll lead in the race for the White House as Hillary Clinton’s plans for a “Convention of hope” descended into bitter infighting and angry protests, with some Democrats saying they would prefer to vote for her Republican rival.

Mrs Clinton is due to become the first female presidential nominee of a major US political party at the Democratic Convention which began in Philadelphia on Monday.

It was billed as a week of optimism laying out a vision of unity and progress for America, contrasting with Mr Trump’s dark and foreboding descriptions of a country in crisis.

As the convention was set to open, a new poll from CNN showed Donald Trump leading Mrs Clinton by 44 per cent to 39 per cent.