National Rifle Association endorses Donald Trump in 2016 presidential race
The Economist Intelligence Unit ranked victory for Republican presidential candidate Donald Trump at 12 on an index where the current top threat is a Chinese economic "hard landing" rated 20 (AFP Photo/Jim Watson)

The National Rifle Association endorsed Republican Donald Trump for U.S. president on Friday and he responded by promising to serve the country's top gun lobby group well.

Trump, his party's presumptive nominee for the Nov. 8 presidential election, praised the NRA and took a swipe at Democratic front-runner Hillary Clinton, saying she wants to abolish the U.S. Constitution's Second Amendment, which guarantees the right to bear arms.

The billionaire businessman has opposed gun-free zones and promised to protect Americans' rights to self-defense.

"I will not let you down," Trump told the gathering in Louisville, Kentucky.

The NRA is the country's leading gun-rights advocacy group.

(Reporting by Doina Chiacu; Editing by Frances Kerry)