Tues­day night’s Demo­c­ra­t­ic debate was large­ly devoid of the per­son­al swipes and par­ty-line lit­mus tests that have dom­i­nat­ed those on the Repub­li­can side. And there was no can­di­date on stage com­mand­ing the star-pow­er of savvy big­ot Don­ald Trump.

As he continues to talk about the benefits of his brand of democratic socialism in contrast to our current capitalist system characterized by massive inequality and poverty, he will have a rapt—and activated—audience.

One test that was laid out ear­ly in the debate, how­ev­er, has real impli­ca­tions for the future of the Demo­c­ra­t­ic Par­ty, and of the role of the Left in U.S. elec­toral pol­i­tics: the ques­tion of iden­ti­fy­ing as a social­ist or capitalist.

That a U.S. pres­i­den­tial debate in 2015 would fea­ture any sub­stan­tive dis­cus­sion on the mer­its of social­ism ver­sus cap­i­tal­ism is itself astound­ing, espe­cial­ly when com­pared to the lan­guage of pres­i­den­tial con­tests in 2008 and 2012, when the social­ist label was fre­quent­ly hurled at Barack Oba­ma as an insult meant to sum­mon images of gulags and work camps. Since at least the Cold War era, a sub­scrip­tion to cap­i­tal­ism has been tak­en as a giv­en for both major polit­i­cal parties.

But here we are, with Bernie Sanders and Hillary Clin­ton dig­ging into the virtues of the dis­parate eco­nom­ic and social mod­els on nation­al tele­vi­sion, watched by some 15.3 mil­lion viewers.

Debate host Ander­son Coop­er began his ques­tion­ing of Bernie Sanders by ask­ing: ​“How can any kind of social­ist win a gen­er­al elec­tion in the Unit­ed States?” Sanders, the self-pro­claimed demo­c­ra­t­ic social­ist, answered by mak­ing the case for a more egal­i­tar­i­an soci­ety where not just income but social ser­vices and health­care are pro­vid­ed demo­c­ra­t­i­cal­ly, regard­less of stature or position:

What demo­c­ra­t­ic social­ism is about is say­ing that it is immoral and wrong that the top one-tenth of 1 per­cent in this coun­try own almost as much wealth as the bot­tom 90 per­cent. That it is wrong, today, in a rigged econ­o­my, that 57 per­cent of all new income is going to the top 1 percent. That when you look around the world, you see every oth­er major coun­try pro­vid­ing health care to all peo­ple as a right, except the Unit­ed States. You see every oth­er major coun­try say­ing to moms that, when you have a baby, we’re not gonna sep­a­rate you from your new­born baby, because we are going to have — we are gonna have med­ical and fam­i­ly paid leave, like every oth­er coun­try on Earth. Those are some of the prin­ci­ples that I believe in, and I think we should look to coun­tries like Den­mark, like Swe­den and Nor­way, and learn from what they have accom­plished for their work­ing people.

When Sanders was asked if he con­sid­ers him­self a cap­i­tal­ist, he respond­ed: ​“Do I con­sid­er myself part of the casi­no cap­i­tal­ist process by which so few have so much and so many have so lit­tle, by which Wall Street’s greed and reck­less­ness wrecked this econ­o­my? No, I don’t. I believe in a soci­ety where all peo­ple do well. Not just a hand­ful of bil­lion­aires.” (This was a par­tic­u­lar­ly iron­ic moment of the debate: Sanders was lam­bast­ing casi­no cap­i­tal­ism while lit­er­al­ly debat­ing inside a Las Vegas casino.)

Coop­er then opened the ques­tion to the rest of the can­di­dates, ask­ing ​“Is there any­body else on the stage who is not a cap­i­tal­ist?,” lead­ing Clin­ton to fire back in defense:

When I think about cap­i­tal­ism, I think about all the small busi­ness­es that were start­ed because we have the oppor­tu­ni­ty and the free­dom in our coun­try for peo­ple to do that and to make a good liv­ing for them­selves and their families. And I don’t think we should con­fuse what we have to do every so often in Amer­i­ca, which is save cap­i­tal­ism from itself. And I think what Sen­a­tor Sanders is say­ing cer­tain­ly makes sense in the terms of the inequal­i­ty that we have. But we are not Den­mark. I love Den­mark. We are the Unit­ed States of Amer­i­ca. And it’s our job to rein in the excess­es of cap­i­tal­ism so that it does­n’t run amok and does­n’t cause the kind of inequities we’re see­ing in our eco­nom­ic system.

This defense of cap­i­tal­ism by the lead­ing can­di­date for the Demo­c­ra­t­ic pres­i­den­tial nom­i­na­tion was any­thing but full-throat­ed. In rec­og­niz­ing that the sys­tem was so flawed that it must be ​“saved from itself,” she sound­ed more like for­mer Greek finance min­is­ter (and self-described ​“errat­ic Marx­ist”) Yanis Varo­ufakis than a tra­di­tion­al main­stream Amer­i­can politician.

As Eliz­a­beth Bru­enig points out at the New Repub­lic, Sanders and Clin­ton have fun­da­men­tal­ly dif­fer­ent visions of how our econ­o­my should be struc­tured: Sanders’ is an egal­i­tar­i­an ​“pro-equal­i­ty plat­form” advo­cat­ing a more expan­sive wel­fare state, while Clinton’s is a Hor­a­tio-Alger style ​“oppor­tu­ni­ty-focused approach” empha­siz­ing increas­ing social-mobility.

This diver­gence was on full dis­play last night. When asked if Clin­ton agreed with Sanders that Social Secu­ri­ty should be expand­ed, for exam­ple, she refused to give a defin­i­tive ​“yes,” instead advo­cat­ing defend­ing and ​“enhanc­ing” the gov­ern­ment-run wel­fare pro­gram, rather than across-the-board expan­sion as Sanders proposes.

While this dis­cus­sion remains a far cry from the Demo­c­ra­t­ic Par­ty dis­tanc­ing itself from its embrace of cap­i­tal­ism (some­thing that will almost assured­ly nev­er hap­pen), the debate — and lev­el of grass­roots sup­port behind Sanders — show that this reck­on­ing could have seri­ous effects on how the par­ty posi­tions itself on eco­nom­ic issues in the future.

And the inclu­sion in the Sanders cam­paign of left­ists gen­er­al­ly crit­i­cal of the elec­toral polit­i­cal process means the pres­sure to con­tin­ue dis­cussing the ben­e­fits of social­ism and draw­backs of cap­i­tal­ism will like­ly con­tin­ue with­in the cam­paign as well. The many activists and orga­niz­ers who are work­ing in the Sanders camp with a robust cri­tique of cor­po­rate cap­i­tal­ism will con­tin­ue to inform how the cam­paign con­structs mes­sag­ing to voters.

And even if Sanders does not win the nom­i­na­tion or pres­i­den­cy, the polit­i­cal edu­ca­tion hap­pen­ing across the coun­try through his cam­paign around issues of gross eco­nom­ic inequal­i­ty, cli­mate dev­as­ta­tion and social injus­tice means there will almost cer­tain­ly be more inter­ro­ga­tion of cap­i­tal­ism than at any time in recent memory.

Sanders is the first can­di­date to bring in one mil­lion dona­tions this ear­ly in a pres­i­den­tial race. He is lead­ing in mul­ti­ple polls in the ear­ly pri­ma­ry vot­ing states of Iowa and New Hamp­shire. And, as pun­dits, donors and atten­dees to his mas­sive ral­lies will tell you, he is the Demo­c­ra­t­ic can­di­date with the most ener­gy right now.

As he con­tin­ues to talk about the ben­e­fits of his brand of demo­c­ra­t­ic social­ism in con­trast to our cur­rent cap­i­tal­ist sys­tem char­ac­ter­ized by mas­sive inequal­i­ty and pover­ty, he will have a rapt — and acti­vat­ed — audience.

Hillary Clin­ton remains the front-run­ner, and is a defend­er of cap­i­tal­ism. As her recent­ly tak­en posi­tions against the Trans-Pacif­ic Part­ner­ship and Key­stone XL pipeline show, she can be moved. But if the kind of com­mon­sense dis­cus­sion about demo­c­ra­t­ic social­ism that Sanders helped lead last night con­tin­ues to catch on, the Demo­c­ra­t­ic Par­ty itself could be forced to move clos­er to Bernie.