Is political violence the ‘new normal’ for America?

As if the build-up to the US presidential election hasn’t been dramatic enough, Donald Trump has been targeted in an alleged assassination attempt for the second time in just a matter of months.
 
On a golf course on Sunday afternoon, gun shots were fired from the surrounding shrubbery towards the former president.
 
But, after decades of no political violence towards presidential candidates, is this the ‘new normal’ for America? And how will this affect the election?
 
ITV News Correspondent Robert Moore tells Tom Bradby what you need to know...