Full coverage: 50 Dead in Orlando Nightclub Shooting

In the wake of the deadliest shooting in US history, Republican presidential candidate Donald Trump has claimed that the shooting proves he is 'right on radical Islamic terrorism'.

On Twitter, he called for toughness and vigilance. He also said President Barack Obama should step down for not using the words 'radical Islam' in describing the attack. An FBI official said the shooter might have leanings toward Islamic State's ideology but warned this suspected connection required further investigation.

In his campaign, Trump has proposed a controversial temporary ban on Muslim immigration to the United States to combat the threat of radical Islamist attacks.