Donald Trump rivals 'may not back him as nominee' after rally violence

Republican presidential candidates Marco Rubio and John Kasich have suggested they may not support Donald Trump if he becomes the Republican nominee, as violence at the front-runner's rallies deepened the party's chaotic chasm.

Tensions ran high at Mr Trump's latest rally, when US Secret Service agents briefly formed a protective ring around the candidate, then left the stage and allowed him to continue speaking at an airport hangar near Dayton, Ohio.