Leading US Republican presidential candidate Donald Trump has vowed to veto President Barack Obama's executive actions on guns if winning the White House.

"The Second Amendment, it's so great to me," Trump told supporters at a campaign rally in Biloxi, Mississippi on Saturday. "We're not changing the Second Amendment."

Trump accused Obama of planning an "assault" on the Second Amendment. "I will veto that. I will unsign that so fast.”

On Friday, Obama said he would meet with US Attorney General Loretta Lynch, who heads the Justice Department, to discuss ways of reducing gun violence in the country.

The president said he would meet Lynch on Monday amid reports he intends to take executive action on curbing gun-related deaths and injuries.

Obama is reportedly considering executive actions on gun control because the Republican-controlled Congress has snubbed previous efforts of the Obama administration to tighten gun laws.

The majority of Americans say the most important events of 2015 were the mass shootings in the United States, including the attack in San Bernardino, California, according to an Associated Press-Times Square Alliance poll.

On December 2, in the deadliest mass shooting in the US in three years, 14 people were killed and 22 others were injured when two extremists attacked a center for people with developmental disabilities in San Bernardino.

According to the US Centers for Disease Control (CDC), firearms are the cause of death for more than 33,000 people in the United States every year, a number that includes accidental discharge, murder and suicides.

Elsewhere in his remarks, Trump said he could win the White House, despite the fact that “the Democrats have certain structural advantages.”

“I’m gonna win states that they never even thought about winning,” he stated, citing his huge rallies as proof of his nationwide popularity.

About a dozen Republicans are seeking their party’s nomination for president, but Trump continues to lead the crowded GOP field despite making controversial remarks against Mexican immigrants, women and Muslims.