US, presidential hopeful Donald Trump has said his supporters would riot if he was denied the Republican nomination despite winning the popular vote. Some Republicans have signalled that they would be open to a brokered convention, where party officials, not voters, would chose the nominee. That would only take place if Mr Trump fell short of the 1,237 delegates needed to secure the nomination. It is unclear if he can hit that threshold before the convention.
Mr Trump has at least 646 delegates and is favoured to win many coming contests, but challenges from opponents Texas Senator Ted Cruz and Ohio Governor John Kasich have blunted his momentum. On Tuesday, Mr Trump won primaries in four states, Florida, Illinois, Missouri and North Carolina. Yet a win by Mr Kasich in Ohio raised the possibly that Trump’s delegate count could fall short.