Such an attack might give some progressive Democrats pause, but if deployed in Clinton’s defense, they would seem to validate the feeling among some liberals that Clinton is a DINO—a Democrat in name only, practically a Republican. And it would tend to undermine her own, measured steps to adopt more progressive policies.

Clinton’s allies may be right that the socialist label would be an albatross for Sanders—and for down-ballot Democrats—in the general election. Last summer, a Gallup poll found that 50 percent of Americans would refuse to vote for a socialist for president—lower even than a gay candidate, a Muslim, or an atheist. (Greg Sargent goes into more detail about the general-election implications of the “socialist” label.) But the Clinton surrogates are trying to make a general-election argument during a primary, which can be a tricky business. The theory is that Democrats tend to gravitate toward a more electable candidate—as demonstrated by primary voters’ flight from Howard Dean to John Kerry in 2004. (And how’d that work out for you? the idealists snort.) Sanders obviously believes this theory, to a certain extent: His campaign has seized on polls that show him beating Republican candidates in head-to-head matches, sending out press releases with titles like “Electability Matters.” (There are good reasons to be skeptical of such head-to-head polling, as I explained here.)

Besides, Democratic primary voters are likely less attuned to the vulnerabilities of the s-word than Carville, et al., might hope. Steve Israel isn’t wrong that Sanders has struggled to explain to a wide audience what exactly he means when he says he’s a “Democratic socialist,” but Democratic primary voters aren’t worried*. In the same 2015 Gallup poll, 59 percent of Democrats said they’d vote for a socialist. Or just look at key Democratic demographics like young people and African Americans. Broken down by age, 69 percent of 18-to-29-year-olds agreed, as did 50 percent of those from 30-49. Gallup didn’t break those numbers out by race, but a Pew survey in 2011 found that more than half of black Americans had a positive view of socialism.

A Bloomberg News/Des Moines Register poll conducted last week offered even more piquant evidence. Among Iowa Democrats, 43 percent described themselves as “socialist”—a solid bit more than the 38 percent who self-identified as “capitalist.”

To some extent, Sanders may be capitalizing on changing attitudes since the Great Recession—lingering anger among progressives about the slow recovery and about the way financial institutions got off mostly scot-free. But he’s also probably driving the increased acceptance of socialism. In early May, about a week after Sanders announced his candidacy, YouGov found Democrats evenly divided on socialism vs. capitalism, 43-43. In mid-October, with Sanderistas in full swing, that had switched to 49-37. Republican messaging guru Frank Luntz sees a similar shift, and attributes it to the Sanders candidacy.