Could Nikki Haley beat Trump to the Republican presidential nomination?

Donald Trump might look as if he’s got the Republican presidential nomination in the bag – but former UN ambassador Nikki Haley is determined to put up a challenge.

She’s just won the backing of two billionaire brothers – and is seeking to build up support among moderate and independent voters, who fear that another Trump campaign will polarise the country still further.

But it’s an uphill battle – as our Washington correspondent Siobhan Kennedy reports.