Over in the US, the biggest day of this year's primary campaign is under way as 16 states cast their votes.

Strong performances from Donald Trump and Joe Biden indicate that the two front-runners for president have been determined.

American pollster Henry Olsen says Nikki Haley has no hope left of becoming the Republican nominee.

"This was actually a collection of states that she could have done well in if she had strength, but the fact that she lost most of them- that shows this is a campaign that should be over." 

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