Obama in Orlando to console grieving families

President Barack Obama arrived in Orlando, where he will console loved ones devastated by a shooting rampage that has fueled America's culture wars and a fresh push for gun controls.

Air Force One touched down shortly before 1:00 p.m. (1700 GMT) in Florida, where Obama will call for national unity and meet families whose lives have been ripped apart by a tragedy of national proportions.

The massacre of 49 people at the Pulse nightclub last Sunday was the deadliest mass shooting in the history of a country that is depressingly familiar with such events. Another 53 people were wounded.

"This will be, I think, an emotional trip," White House spokesman Josh Earnest said.

In a rare symbolic show of bipartisanship, Obama arrived with Republican one-time presidential hopeful Marco Rubio and was greeted on the tarmac by Republican Florida governor Rick Scott and Vice President Joe Biden.

Obama and Biden are slated to meet emergency medical crews and hospital staff who laboured to save lives in the chaotic hours after the massacre by gunman Omar Mateen, a 29-year-old Muslim American of Afghan descent.

Mateen was killed in a police raid, but his motivation and how he came to possess an special forces assault rifle remain deeply contentious.

Mateen pledged allegiance to the leader of the Islamic State group in a 911 call during the attack.

The IS group then claimed responsibility for the shooting, and FBI agents believe that Mateen was radicalised by following extremist propaganda online.

That has prompted Republicans to call for tougher counterterrorism measures and for the Obama administration to do more to fight the Islamic State group.

The White House says coalition forces and allies are making gains against the group's strongholds in Syria, Iraq and Libya.

But Republican arguments were given credence by Obama's own CIA director John Brennan, who warned the group retains the ability to conduct attacks around the world.

"Unfortunately, despite all our progress against ISIL on the battlefield and in the financial realm, our efforts have not reduced the group's terrorism capability and global reach," he told senior US lawmakers.