Finally, there’s no significant pro-gun control power within the GOP. Sure, the NRA is organized and donates heavily to conservative politicians, and Fox News is likely to bash gun control measures. But beyond that, there is no countervailing force in the party promoting gun control, offering resources and money to help Republicans who take that stance. In this sense, gun policy in the GOP is akin to abortion on the Democratic side — there’s a sizable bloc of Democrats who favor limits on abortion, but there’s no counterweight to abortion rights groups like Emily’s List and Planned Parenthood.

“The NRA is the model of a great powerful American interest group,” said Matt Glassman, a congressional expert at the Government Affairs Institute at Georgetown University. It has millions of members, is well organized and exerts constant pressure, he said.

“More importantly, they appear to have a huge number of single-issue voters that they have cultivated and keep motivated,” Glassman said. “They can credibly threaten to have a fair percentage of GOP primary voters literally walk away from a representative over their issue. That’s so much more valuable than having an opinion majority on your side. … The power of single-issue voters is one of the most underappreciated aspects of politics.”