Though Hillary Clinton is all but mathematically guaranteed to best Bernie Sanders for the Democratic nomination, the race is only getting more contentious in its closing stages.

Mr Sanders is facing calls from Democratic Party leadership to repudiate the actions of some of his supporters, who wrecked havoc at a party convention in Nevada over the weekend and have issued threats to party officials.

They feel that party leaders rigged the nomination battle in favour of Mrs Clinton, and that Mr Sanders is being robbed of what should rightfully be his.

Harry Reid, the top Senate Democrat, urged Mr Sanders to confront the violence and threats in Nevada, saying his response would be a "test of leadership".