Republican Ben Carson has confirmed his backing for presidential frontrunner Donald Trump in the race for the White House.

He is the second former presidential candidate to announce his support for the billionaire businessman.

Carson, a retired neurosurgeon, dropped out of the presidential race on 4 March.

He made the announcement at a joint news conference with Donald Trump in Florida on Friday.

New Jersey Governor Chris Christie, is also backing Trump after earlier dropping out of the race for the party's nomination.