A New Jersey judge has ruled that Texas Republican Senator Ted Cruz meets the constitutional requirements to be president and may appear on the state's presidential primary ballot.

Republican voters fed up with Washington have feted billionaire businessman Donald Trump as the ultimate 2016 outsider, making him the front-runner for the GOP nomination.

Donald Trump belittled the physical appearance of fellow Republican US presidential candidate Carly Fiorina, saying: “Look at that face. Would anyone vote for that?”