Republicans are fond of hurling the epithet "socialist" at Democrats — even those Democrats who pursue policy reforms originally hatched by conservatives, who push hard for free trade agreements, and who appoint cabinet secretaries and top advisors with strong ties to the financial sector.

This "socialist" name-calling is usually nonsense. But now Republicans — and all Americans — are finally going to get to see the real thing in action. With Bernie Sanders competing seriously against Hillary Clinton for the Democratic nomination, it looks like all of us will have at least the better part of a year to observe the behavior of that rarest of all endangered political species: a bona fide American socialist.

But what does that even mean? Just what kind of a socialist is Bernie Sanders?

To help answer these questions, I spoke to Jack Ross, author of an important (and now extremely timely) new book, The Socialist Party of America: A Complete History.

"Sanders is squarely in the tradition of the Socialist Party politicians elected in the first half of the 20th century in places as far flung as Milwaukee; Schenectady, New York; Butte, Montana; Minneapolis; Reading, Pennsylvania; and Bridgeport, Connecticut," says Ross. These politicians succeeded by focusing above all on "constituency service and clean government" — governing as small-d democrats in the Jeffersonian tradition of public service. That has been Sanders' approach since he got himself elected as mayor of Burlington, Vermont, in 1981 and on through his time in the House and Senate.

Ideologically speaking, this places Sanders at some remove from the New Left that rose to prominence during the 1960s. While the New Left at first positioned itself as a more stringently leftist alternative to the Old Left stance of the Socialist Party, which was already moribund by the late 50s, the New Left's alliance with the civil rights movement led it rather quickly to embrace identity politics — an emphasis that entered the Democratic bloodstream when the party's left-wing faction took control in 1972.

The emphasis on identity politics was never particularly popular with the American people. This is something that the centrist Democratic Leadership Council and its greatest electoral success story (Bill Clinton) understood very well. But rather than abandoning identity politics in favor of a return to class-based mobilization for political and economic reform, DLC Democrats went in the opposite direction — holding on to identity politics while embracing free markets and the financial sector. That's today's Democratic Party: centrist (neoliberal) on economics and radical (formerly New Leftist) on culture (race, gender, and sexual orientation).

"Bernie Sanders' political pedigree runs against the grain of all this," says Ross. "Beginning in a radical dissenting faction of the Young People's Socialist League in the early 1960s, and then squarely situated in the most impeccably small-d democratic segment of the New Left," Sanders has worked "to revive the possibilities for a new party and a spirit resembling the historic socialist movement" whose greatest heroes are "the original middle American radical Eugene V. Debs and the quintessential progressive isolationist Norman Thomas."

This places Sanders strongly at odds with "the idolatry of identity politics" that, according to Ross, has helped make radicalism "so painfully irrelevant in the post-9/11 era." In place of our familiar, obsessive focus on race, gender, and sexual orientation — an emphasis that stands in the way of fostering class-based solidarity — Sanders is likely to encourage the forging of ties among the poor and working class of all races, ethnicities, genders, and sexual preferences for the sake of reining in those who wield economic power in the United States and rig its political system for their own benefit.

One way to describe this agenda is to say that it sounds like something a Scandinavian social democrat would propose. There's some truth to this, in the sense that Sanders' support for a single-payer healthcare system, public financing of elections, higher taxes, and more government regulation and spending to combat burgeoning inequality harmonizes very well with the platforms of any number of European socialist parties. That's no doubt why so many commentators — and the candidate himself — have chosen to emphasize that angle in talking about his nascent presidential campaign.

But it's important to recognize that there are American antecedents to these positions — in the Jeffersonian egalitarian ideal of an active, engaged citizenry, and in the Socialist Party of America. In many ways, Sanders' emphasis on citizen virtue and good-government initiatives to control the influence of the super-rich and Big Business on our political system is as American as can be — though it's a kind of Americanism that we haven't seen for a very long time. In that sense, Sanders might be the most conservative candidate running in either party this election cycle.

Does that kind of throwback politician stand a chance today? Sanders' impressive early haul in (mostly tiny individual) campaign donations shows that, at least for a while, social-media-fueled grassroots organizing can give an outsider a boost. But in the end, it's extremely unlikely he'll be able to overcome the Clinton juggernaut.

That doesn't mean the Sanders campaign won't be important. "What Sanders can and likely will do, though it's not necessarily his intention," says Ross, "is pry open the contradictions in contemporary liberalism." From the time of the New Deal, liberalism has portrayed itself rhetorically as a pragmatic effort to institute something like the agenda of the old Socialist Party. Yet over the past few decades, liberalism has evolved into something very different: an ideology that primarily speaks and appeals to members of public-sector unions, a slew of identity-based grievance groups, and highly credentialed upper-class professionals — all the while continuing to employ the same populist, small-d democratic rhetoric it did in the mid-1930s.

Sanders is well placed to call liberalism's bluff — to challenge Hillary Clinton and the rest of her party to confront the deep tension between what it purports to stand for and the policies for which it repeatedly settles.

No matter how Sanders does in the final vote tallies, having an old-style socialist gadfly buzzing around, drawing drops of blood from the candidate the Democratic establishment would very much like to see anointed, can't possibly have anything other than a salutary effect on our increasingly inbred, sclerotic political system.

I'm not a socialist myself. But I'm very happy Bernie Sanders is running for president.