Bernie Sanders has urged his supporters to back Democratic rival Hillary Clinton, as the party's national convention gets underway.

His comments drew jeers and boos for the party's presumptive presidential candidate at the start of its convention in Philadelphia.

But Mr Sanders warned of the 'danger' of allowing the Republican nominee the keys to the White House. To which Donald Trump replied in a tweet; 'Bernie Sanders totally sold out to crooked Hillary Clinton. All of that work, energy and money, and nothing to show for it! Waste of time.'

The convention itself is mired in controversy after emails indicated that the Clinton campaign had tried to undermine Sanders bid for the Democratic nomination.

However Sanders has decided to publicly support Hillary Clinton: 

Michelle Obama has also backed Clinton for the White House, in a speech at the Convention yesterday:

“Because of Hillary Clinton, my daughters...can take it for granted that a woman can be president.” —@FLOTUS pic.twitter.com/bCezjrX9W5

— Hillary Clinton (@HillaryClinton) July 26, 2016