Donald Trump hasn't always championed the NRA's agenda

The White House is a gun-free zone, which means visitors are not permitted to bring weapons inside. On Friday, Donald Trump told the NRA he would eliminate gun-free zones as he won the group's endorsement.

Trump also said that he would expand gun rights.

"The only way to save our Second Amendment is to vote for a person that you all know, named Donald Trump. Okay? I will tell you -- I will never let you down."

Trump says he would allow guns on school grounds and other public facilities where they are currently banned. But Trump hasn't always championed the NRA's agenda.

In 2000, Trump wrote "I support the ban on assault weapons and ... a slightly longer waiting period to purchase a gun," two positions he now opposes.

And after the Sandy Hook Elementary School massacre, Trump applauded President Obama's speech calling for stricter gun laws on Twitter.

Now, he is attacking his likely general election opponent.

"Crooked Hillary Clinton is the most anti-gun, anti-Second Amendment candidate ever to run for office and, as I said before, she wants to abolish the Second Amendment."

Clinton supports universal background checks, smaller magazine cartridges for automatic firearms, and an end to immunity for gun manufacturers.

"Ninety-two percent of Americans support universal background checks ... I am so hoping that gun owners would be willing to take the lead in pushing for the kind of changes that we need," Clinton said on the campaign trail.

As for Trump's call to abolish gun-free zones, the venue for the NRA convention, Freedom Hall, is one of them -- as are some Trump properties. Clinton's campaign called the idea dangerous and radical, as Clinton prepares to meet Saturday with victims of gun violence.