Like gay mar­riage, ac­cess to free con­tra­cep­tion un­der the Af­ford­able Care Act, leg­al status for un­doc­u­mented im­mig­rants, leg­al­ized abor­tion, and ac­tion against cli­mate change, gun con­trol now helps knit to­geth­er a Demo­crat­ic co­ali­tion bound largely by shared cul­tur­al val­ues—while fur­ther ali­en­at­ing the cul­tur­ally con­ser­vat­ive groups of older, blue-col­lar, and non­-urb­an whites in­creas­ingly pivotal to Re­pub­lic­an elect­or­al for­tunes.

Gun con­trol thus joins that lengthy list of cul­tur­al di­vides that is largely help­ing Demo­crats among white-col­lar urb­an­ized voters (es­pe­cially wo­men) like those in North­ern Vir­gin­ia or the sub­urbs of Phil­adelphia and Den­ver, but fur­ther weaken­ing them among blue-col­lar and ex­urb­an and rur­al voters (es­pe­cially men) in the same states and bey­ond. In many key swing states, the rising vis­ib­il­ity of gun is­sues in 2016 could ex­acer­bate the sharp urb­an/rur­al di­vide that defined such closely de­cided con­tests as the nar­row Demo­crat­ic vic­tor­ies in the 2014 Col­or­ado gov­ernor’s race and Vir­gin­ia Sen­ate race.

Demo­crats largely muted their ad­vocacy of gun con­trol after the 2000 presidential elec­tion, when many in the party con­cluded that it drove away blue-col­lar whites and con­trib­uted to Al Gore’s photo-fin­ish de­feat by George W. Bush. But Obama’s pro­pos­al—and the com­par­ably am­bi­tious plans that Hil­lary Clin­ton has ad­vanced—shows how much changes in the party’s co­ali­tion have changed its cal­cu­la­tion on the is­sue.

Since 2000, Demo­crats have grown far less de­pend­ent on the blue-col­lar whites who are the most res­ist­ant to gun-con­trol meas­ures, and have re­placed them with grow­ing groups like people of col­or and col­lege-edu­cated white wo­men more open to the idea. In one telling meas­ure, whites without a col­lege edu­ca­tion provided about half of Bill Clin­ton’s votes in the 1992 pres­id­en­tial elec­tion—but only one fourth of Obama’s in 2012. That shift has en­cour­aged Demo­crats to press the is­sue more force­fully. Hil­lary Clin­ton is now even run­ning ads in New Hamp­shire tout­ing her sup­port for “uni­ver­sal back­ground checks” for gun purchases and in­sist­ing, “How many people have to die be­fore we ac­tu­ally act, be­fore we come to­geth­er as a na­tion?”

The res­ult is that after years in which Re­pub­lic­ans were more con­fid­ent than Demo­crats in de­bat­ing gun-con­trol ques­tions, the is­sue now en­er­gizes each side’s co­ali­tion. Gun con­trol is still a dif­fi­cult is­sue for Demo­crats in the struggle for con­trol of Con­gress, largely be­cause the Sen­ate’s small-state bi­as provides dispro­por­tion­ate lever­age to the rur­al states where it is most un­pop­u­lar.

But at the pres­id­en­tial level, Demo­crats ap­pear cer­tain to wage the is­sue more aggress­ively than in any cam­paign since 2000; they have re­gained con­fid­ence that it is a win­ning ar­gu­ment with the groups, and in the states, that they can actu­ally win. The price, as the chart above shows, is that it fur­ther ali­en­ates the cultur­ally con­ser­vat­ive whites already mov­ing away from Demo­crats around other is­sues—a trend that could prove most chal­len­ging for the party’s pres­id­ential nom­in­ee in aging, heav­ily blue-col­lar Rust Belt battle­grounds like Ohio, Michigan, and Wis­con­sin.

This article is part of our With Great Power project, which is supported by a grant from the Joyce Foundation. It appears courtesy of National Journal.