Things like closing the so-called gun show loophole or restricting the mentally ill from buying guns are supported by huge majorities of Republicans and Democrats. In a Quinnipiac University poll conducted in June , 94%(!) of Americans supported the idea of all gun purchases being subject to background checks -- including 92% of people who live in a home with a gun. A Pew poll from this past summer showed that 89% of gun owners and 89% of non-gun owners support preventing mentally ill people from buying guns.

Typically, on issues where nine in 10 Americans agree, Congress find a way to act. After all, the job of members of Congress, broadly speaking, is to represent the interests of their constituents. And, in raw political terms, doing something that 90%+ of the public wants is a smart move.

So, why has no major -- or, really, even minor -- gun control passed Congress since the assault weapons ban in the mid-1990s? And why, in the wake of the Pulse nightclub shooting in 2016, did Democratic Sen. Chris Murphy's legislation to close the gun show loophole and ban firearms sales over the Internet fail -- with all but one Republican opposing it and three Democrats also voting against it?

The most-common answer is the National Rifle Association. There's no question that the NRA has built a very powerful lobbying and political machine in Washington -- and shown a willingness to support those who support them and go after those who don't.

But it isn't the NRA's lobbying or political donations that are responsible for why nothing gets done. It's the broader idea -- which the NRA and lots of Republican elected officials push -- that, at root, any attempt to make gun laws stricter amounts to the first step on a slippery slope that eventually leads to liberals coming to your house and confiscating your guns.

"Hillary wants to abolish, essentially abolish, the Second Amendment," Donald Trump said at a rally in North Carolina in August 2016. It was a claim he repeated time and again on the campaign trail as a way of amping up the stakes -- and the threat -- in the election.

Trump has continued to beat that drum in office. "If Crooked Hillary got elected, you would not have a 2nd Amendment, believe me," Trump told a rally in Alabama last month

JUST WATCHED Trump in Alabama in September: You'd turn over your rifles to Clinton Replay More Videos ... MUST WATCH Trump in Alabama in September: You'd turn over your rifles to Clinton 00:48

This claim is not true. Clinton expressly stated that she believes "gun ownership is part of the fabric of many law-abiding communities" while also noting "too many families in America have suffered from gun violence."

But none of that is the same thing as Clinton calling for a mass round-up of guns or repealing the 2nd Amendment.

This accusation is not unique to Clinton. Former President Barack Obama who, like Clinton openly favored more restrictive gun laws, was regularly accused of wanting to collect everyone's guns.

Here's what he said about that last year:

"First of all, the notion that I or Hillary or Democrats or whoever you want to choose are hell-bent on taking away folks' guns is just not true. And I don't care how many times the NRA says it. I'm about to leave office. There have been more guns sold since I have been president than just about any time in US history. There are enough guns for every man, woman and child in this country. And at no point have I ever, ever proposed confiscating guns from responsible gun owners. So it's just not true."

What's difficult is that no matter how many times Clinton or Obama -- or any other prominent gun control supporter -- insists publicly that they have no interest in some sort of mass gun seizure, it doesn't change the minds of those who believe the idea. Those folks think that Democrats have a secret plan -- that the likes of Clinton and Obama deny publicly -- to get rid of all guns in the country.

While these comments are surely sentiments with which gun rights supporters disagree, they don't amount to any sort of broad-scale conspiracy within the Democratic Party to round up all the guns in the country. (Aside from the lack of actual evidence of this plan, the sheer logistics of such an effort would be mind-bogglingly complex.) But, conspiracy theories are not built on rational evidence. They are built on irrational fear.

Fear, of course, is a hugely powerful political motivator. The idea of roving bands of liberals grabbing for your guns and robbing you of a fundamental freedom is scary to lots of people. And so, when a group or a politician suggests that any attempt to restrict gun rights or close loopholes is the first step in the execution of the broader gun-collection plan they have always warned you about, it's easy to see why so many gun rights supporters react the way they do.

But conspiracy theories aren't facts. And the facts make clear that the idea of some sort of national gun seizure isn't something any politician is interesting in.

JUST WATCHED President Obama: Yes, 'plot' notion is a conspiracy Replay More Videos ... MUST WATCH President Obama: Yes, 'plot' notion is a conspiracy 02:32

Cooper: "Is it fair to call it a conspiracy?"A lot of people really believe this deeply. They just don't trust you."

Obama: "I'm sorry, [Anderson]. Yes it is fair to call it a conspiracy. What are you saying? Are you suggesting that the notion that we are creating a plot to take everybody's guns away so that we can impose martial law is [not] a conspiracy? Yes that is a conspiracy! I would hope that you would agree with that. Is that controversial I'm only going to be here for another year. When would I have started on this enterprise, right?"