Hillary Clinton said Monday that congressional Republicans and the National Rifle Association are complicit in the United States' gun violence epidemic after a lone gunman slain 59 people at a country music festival in Las Vegas.

Clinton then said "of course they are" when asked by host Igor Volsky, the vice president of progressive think tank Center for American Progress, whether those parties were "complicit" in the "gun epidemic."

"It is a sign of the deep dysfunction of this government and this Republican Party that has been taken over by extreme elements to the point that they are doing whatever they are told to do," Clinton said on the Center for American Progress' podcast, referring to the pro-gun group's influence on the policy debate in the wake of the 2016 Pulse Nightclub shooting. "There is no room for discretion, for conscience. It is heartbreaking."

"When people are being killed and gun-makers and -owners are being given a free pass, there is something so fundamentally wrong with our political system," she added.

Clinton called Sunday night's shooting at the Route 91 Harvest festival, which left more than 500 injured, "terrible and sickening."

Her party needed to be fearless when pushing for gun control measures like ammunition capacity limits and a gun registration program, the failed 2016 Democratic presidential candidate said.

She also slammed President Trump for rolling back Obama-era regulations, such as rules that stipulated when mental health records and blindness could prevent gun sales, as being "beyond absurd, this is evil."

"We've got to do a better job of getting prepared to defend these positions and to recognize that 90% of Americans agree with us, and a very overwhelming super-majority of gun owners agree with us," Clinton said.

"So, there's a long list of things we should do, but until we change the political calculation for a lot of elected officials, and get a much more vigorous campaign undertaken by Moms Demand Action and the Brady folks and everybody else, we're still just going to be fighting rear-guard actions."