For over a decade, the dominant theme in European politics has been the emergence of movements that seek to dramatise and exploit social divisions through crude and aggressive sloganeering. One of the trendsetters in this regard was the comedian Beppe Grillo, who in 2007 held an anti-establishment rally billed as “Vaffanculo Day” (Fuck-off Day). That mass protest in Bologna launched a populist wave in Italy, eventually leading to the rise of the anti-immigration politician Matteo Salvini, whose hard-right League party – currently out of government – is polling far ahead of its rivals.

Progressives have despaired at the apparent inability of centre-left politicians to find the vocabulary and imagination to challenge the divisive and often violent rhetoric of figures such as Salvini and Marine Le Pen. But help may be at hand, in the form of a burgeoning grassroots movement in Italy that takes the symbol of a fish as its inspiration. Appropriately, it began in Bologna.

The “Sardine” movement emerged as a response to Mr Salvini’s bid to win power in traditionally leftwing Emilia-Romagna, in crucial January elections. As the League’s leader headed for Bologna this month, a group of residents called for a flashmob of 6,000 people to pack the central square, sardine-style, to oppose what organisers described as the hard right’s politics of division. Around 15,000 people turned up, a considerably larger crowd than the one attending Mr Salvini’s campaign launch. What began as a local act of brio has now become a national phenomenon. Wherever Mr Salvini goes, Sardines stage their own gatherings, waving cardboard cutouts of the fish that has become their brand. Further anti-Salvini rallies are planned in Turin, Milan, Naples, Florence and Rome.

Is this the first popular insurgency against rightwing populism? Movements come and go, particularly in the age of social media. But what is unique about this one is the register in which it attempts to convey its message. Banners and other signs of political affiliation are banned from rallies. This is to foster an inclusive spirit, but also to emphasise a civic dimension to the protests. The main goal of the rallies is to reassert values of tolerance and moderation in the public square. Participants are encouraged to ignore rather than respond in kind to abuse either on social media or in person. One of the Sardines’ Facebook pages tells Mr Salvini: “For years you poured lies and hate over us.” In the piazzas, the preferred response tends to come in the form of a collective singsong, usually involving the old Resistance favourite, Bella Ciao.

A recent poll found a majority of respondents judged the subversive power of the Sardines a greater threat to Mr Salvini’s ambitions than either the Democratic party or the Five Star Movement. Whatever the future holds, there are lessons here that go beyond Italy. When politics is conducted with imagination and panache, anti-populist messages can cut through. And if the success of the Sardines has tapped a deep desire among Italians to move beyond the coarsened language of the country’s populist moment, the same could surely apply elsewhere. More Sardines are needed to swim with this tide.