Since the days of Joe McCarthy’s communist witch-hunts, American politics has rarely seen a “red scare” to match that greeting the surging popularity of Bernie Sanders.



The self-declared socialist senator from Vermont, who is now challenging Hillary Clinton for the Democratic presidential nomination, is not even hiding under the bed; he would sooner jump up and down on the mattress than disown his leftwing past.



He remains a long-shot to win the Democratic party’s nomination, let alone the White House, but moderate colleagues in the Senate warn nonetheless that the media is failing to expose his extreme liberal agenda.

Republican opponents argue that the sight of an “honest-to-goodness socialist” even gaining on Clinton in the polls proves just how dangerously radical the Democratic party has become.

Yet by international or historical standards, it can be hard to detect the traditional hallmarks of socialism in the increasingly popular, and populist, rallies of Comrade Sanders.

His proposals for Canadian-style universal healthcare and subsidised higher education, though bold by US standards, would once not have looked out of place in the manifesto of the British Conservative party – never mind those of resurgent European leftists like Syriza of Greece or Podemos of Spain.

Similar promises to tackle the power of investment banks and restore the earnings potential of the middle class are made not just by European social democrats but other Washington politicians too, such as Elizabeth Warren.



And while calls for progressive tax rises and modest hikes in social security and the minimum wage might echo the early French socialists who first wrote “from each according to his ability, to each according to his need”, they are a far cry from the policies of the Marxists who later used that slogan to justify nationalising the commanding heights of industry.



Supporters of Senator Bernie Sanders cheer at a campaign rally on Monday in Portland, Maine. Photograph: Robert F Bukaty/AP

For though he talks of the need for a “political revolution” and may have briefly flirted with nationalisation in the 1970s, Sanders has always stressed his roots in the American tradition of democratic socialism rather than allow any room for McCarthyite confusion.



Whether this would qualify as socialist on the streets of Paris or in the mines of South Wales, those who have studied the American history of the term claim he therefore deserves the benefit of the doubt.



“Given that socialism hasn’t exactly been a thriving concern in the United States and given that it’s often hurled as an insult, for someone to voluntarily take on the term, I cut them some slack,” says Eric Arnesen, a history professor at George Washington University, who points to faith in government to correct economic injustice as the key hallmark of the word.



“If you check enough of those boxes, and I think Sanders does, then you are entitled to call yourself a socialist and be called one by your opponents.”



Jack Ross, author of a new history of the Socialist Party of America, agrees that Sanders draws inspiration from the party’s heyday in the 1920s and 1930s, though he avoided the bitter splits that dogged the national movement in the 1970s and 1980s by escaping to the calmer climes of Vermont.



“Even if he is not the inheritor, he is provoking the right questions,” says Ross. “For all the ways that Bernie Sanders is a product of a very different time and place, he represents enough of a link to the [American socialist] past.”



There are some within the US who are more willing to question these credentials, however. Supporters of the Green party, for example, have accused Sanders of selling out by dropping his independent status – the label under which he has been elected to Congress since 1990 – to seek the Democratic nomination.



A series of articles in the radical Jacobin magazine also point to the failure of other progressive champions such as George McGovern and Howard Dean to make much headway inside a party dominated by the Washington establishment.



“Like many leftists before him, the Democratic party has co-opted and changed Sanders, using him to help hinder the development of a genuine alternative to the capitalist parties,” added Ashley Smith in Socialist Worker.



But Sanders has been adamant from the outset of his campaign that he does not want to follow third-party candidates like Ralph Nader and risk letting in a Republican president by splitting the progressive vote, which is why he stood as a Democrat and not an independent, he said.



Perhaps a more interesting question therefore is not whether Bernie Sanders qualifies as a socialist among the purists but whether he can rehabilitate the word as a more neutral political term in the capitalist heartlands of America.



Bernie Sanders speaking to a crowd in Burlington, Vermont, in May. Photograph: Andy Duback/AP

“He has the capacity to reintroduce the word socialism without its negative connotations,” argues Arnesen. “I don’t know how likely it is, but it is certainly a possibility that in the current environment will lose some of the sting it once had.”



He believes it may help explain why Sanders is so willing to continue being described in this way, despite the word’s past toxicity.



“If you have called yourself over the years a socialist and if your opponents are hurling the term at you, you can either run from the term and then you look like a flip-flopper or you can take the label and say: ‘And your point is? It’s not a dirty word’,” adds Arnesen.



Ross agrees it is time to bury the semantic dogma and rescue the word from critics on the right in the same way that “liberal” gradually made a recovery after George HW Bush used it to bash Michael Dukakis so effectively in the 1980s.



“As far as I am concerned the word ‘socialist’ is as elastic in its meaning as liberal and conservative,” he argues. “To a large extent what’s happened with the word socialism is a boomerang effect after the way of a lot of right-wingers flung it at Obama.”

But beyond simply expanding the narrowly permissible lexicon of the Washington beltway, those who have studied the way American socialists have been traduced as communist sympathisers over the decades hope Sanders lack of shame over the S-word might signal a more historic shift.

“A generation after the cold war, there deserves to be a reexamination of socialism on its own terms,” says Ross. “It will have a salutatory effect on the liberal left.”