For years, European radicals greeted the idea of a “left” in America with a snort. After all, the Democratic party was certainly not social democratic in European terms. A figure such as Barack Obama, a symbol of progressive politics and a man whose presidential victories were transformative in American terms, would not seem too out of place on the liberal wing of the British Tory party.

Play Video 3:47 'This is the beginning': Alexandria Ocasio-Cortez's victory speech – video

This lack-of-left culture explains in part the excitement that greeted the recent victory of Alexandria Ocasio-Cortez in the Democratic primary in New York’s 14th congressional district. A woman unafraid to call herself “socialist” – until recently, and Bernie Sanders excepted, almost as toxic a term in US electoral politics as “atheist” – seems certain to win in November’s congressional midterm election.

Facebook Twitter Pinterest Andrew Gillum, the Democratic candidate for the governorship of Florida. Photograph: Christopher Aluka Berry/Reuters

The fervour that greeted Ocasio-Cortez’s victory – and of figures such as Andrew Gillum, the new Democratic candidate for the governorship of Florida – was certainly exaggerated. Her success says as much about the arrogance and moribund character of the Democratic establishment as it does about the popularity of her political vision. Whether her approach can mark an authentic shift in politics, or help resurrect a form of working-class politics long missing in America, remains to be seen. Nevertheless, the debate is welcome.

The shifting sands of left politics on both sides of the Atlantic were highlighted last week by the news that Tribune, the almost defunct Labour-left publication, has been bought by the American radical magazine Jacobin. Its founder and editor, Bhaskar Sunkara, says his politics was shaped by “engagement with the British left”. At a time when the left-right divide has become so blurred in Europe, and there is talk of a new centrist party in Britain, the stirrings of a different debate in the US will be something to watch.

• Kenan Malik is an Observer columnist