There was mass fury at the Senate for filibustering a weakened gun background checks bill that had been driven by the outrage that one man with an AR-15 could kill 20 schoolchildren. What's more interesting is whether all that rage will end up changing anything on its own. Those who were pessimistic that Congress would ever take up gun regulations were felt vindicated. The gun bill was doomed from day one, The New York Times' Jennifer Steinhauer wrote on Thursday, because red-state Democrats have calculated that "the political fury of opponents would not be offset by support from those who favor tighter controls." Has that calculation changed? And would it apply to Republicans?

Supporters of more gun control promise that it has. Former Rep. Gabby Giffords, the victim of an assassination attempt in 2011, wrote in The New York Times, "Speaking is physically difficult for me. But my feelings are clear: I'm furious… I’m asking citizens to go to their offices and say: You’ve disappointed me, and there will be consequences." President Obama said, "you need to let your representatives in Congress know that you are disappointed, and that if they don’t act this time, you will remember come election time." The New York Daily News put together the photos of all the senators who voted to filibuster the bill, inviting readers to "Meet the cowards." "This fight has just begun," Joe Scarborough said on MSNBC Thursday. "The American people were insulted yesterday." The GOP, he said, "is moving toward extinction." Michael Bloomberg's Mayors Against Illegal Guns promised to air ads attacking the most vulnerable senators up who filibustered the bill and are up for reelection in 2014, as well as House Republicans in suburban districts. When Senate Minority Leader Mitch McConnell's Facebook page posted an image (at right) gloating over the bill's death, the page was filled with thousands of angry comments promising to oust him.

Do they have the power to do that? One of the most interesting explanations for the bill's failure was reported by Politico's Glenn Thrush and Reid J. Epstein. The gun bill failed, their reporting suggests, because the post-election sweep of liberal issues has been too broad:

One senator told a White House official that it was “Guns, gays and immigration - it’s too much. I can be with you on one or two of them, but not all three.”

That's fascinating, because those things are all popular. Background checks had the support of 90 percent of Americans -- and majority support among gun owners. Almost two-thirds of Americans support immigration reform that includes the most controversial measure, a path to citizenship for illegal immigrants. A majority of Americans support gay marriage -- and there is not even any legislation on gay marriage pending in the Senate! But they are not as popular in the rural states who are overrepresented in the Senate.

Which helps explain why gun supporters' cause is so difficult. Mitch McConnell might be nervous about winning reelection in 2014 -- not because he thinks voters see him as too conservative, but because they might see him as too liberal. Even though the Senate overrepresents rural states at the expense of more urban states, the background check bill had majority support, as The Atlantic's James Fallows points out. As the Wire's Philip Bump explains, senators representing as few as 11 percent of the American population could filibuster a bill. On Wednesday, senators representing 37 percent of Americans blocked background checks. Of the 46 senators who voted against the bill (as shown by the Daily News at left), only six come from swing states. Gun control supporters have to change not just senators, but the way the Senate works.