Can progressives push back the rising tide of authoritarianism? Thousands of people gathered in Barcelona this weekend in search of an answer. The occasion was the inaugural Global Progressive Mobilisation – an ambitious initiative backed by the Spanish prime minister, Pedro Sánchez – which drew an impressive cast: Brazil’s Lula, Mexico’s Claudia Sheinbaum, Colombia’s Gustavo Petro and South Africa’s Cyril Ramaphosa, alongside many activists and civil society organisations. There was no shortage of targets in the discussion panels and speeches: Donald Trump, fascism, war, corporate power and Israel’s genocide.

What was striking, though, was who wasn’t there. Europe’s leaders were largely absent. That was inevitable, given that Spain stands alone as the only major European country governed by a meaningfully progressive administration. Keir Starmer’s failure to attend – even if his deputy, David Lammy, turned up – was hardly surprising. Indeed, the political distance between Starmer and a leader such as Sánchez is striking. Once little known beyond his own country, the Spanish PM’s outspoken opposition to Israel’s genocide in Gaza and his unequivocal condemnation of the Iran war have won him respect among European publics and governments across the global south alike.

Whether Sánchez offers a route back for Europe’s embattled social democratic tradition is another question. His speech at the conference echoed themes long abandoned by his peers: denunciations of billionaires, speculators and “techno-oligarchs”, and a blunt declaration that “neoliberal orthodoxy” died in 2008. It is difficult to imagine Starmer proclaiming that “when we progressives reach government, it is not to serve the elites – we put them in their place”.

The crisis of the west cannot be understood without considering the long self-destruction of social democracy. In the 1990s, most centre-left parties embraced neoliberalism – privatisation, deregulation and low taxes on the wealthy. After the financial crash, many imposed or enabled austerity, hollowing out their own political foundations. One consequence was the rise of the far right; in some cases, it was the radical left that surged instead.

After 2008, the Socialist party in Spain – the centre-left, social-democratic party now headed by Sánchez – seemed destined for decline, having committed itself to freezing pensions, cutting public sector pay, slashing investment and other unpopular measures. In the end, rather than being displaced by the insurgent, leftwing party Podemos, they joined forces. Since 2018, Sánchez has been the PM of a progressive coalition government, with the radical left as junior partners.

That government’s achievements have been significant: strengthened labour rights, expanded protections for women and LGBTQ people, sharp increases in the minimum wage and more interventionist housing policies. Podemos and its successor, Sumar, have pulled the administration in a more radical direction, while Spain’s economy is among the fastest-growing in Europe. Yet it is the Socialists who reap most of the credit, while more radical voters grow disillusioned with compromise. You can see why Angela Merkel once boasted of coalition government: “The little party always gets smashed!”

Sánchez’s government faces formidable challenges. It lacks a parliamentary majority, limiting its ability to implement policy, and is beset by corruption allegations that it dismisses as politically motivated. A society scarred by austerity remains deeply unsettled. With an election due next year, polling points towards a possible rightwing coalition led by the increasingly hardline People’s party. The irony is that much of the Socialist establishment once resisted any alliance with a new left that sought to replace it. Now it risks losing power precisely because disillusioned left-wing voters may simply stay at home.

Given these domestic pressures, the government’s investment in international organising might seem misplaced. But the Global Progressive Mobilisation reflects a growing recognition: the far right is a transnational force that can only be confronted through international solidarity. Despite their nationalist rhetoric, rightwing movements have proved adept at cross-border cooperation. Their opponents must do the same. The Mobilisation explicitly casts itself as a counterweight to the Conservative Political Action Conference (CPAC), long associated with figures such as Hungary’s Viktor Orbán.

The initiative comes amid flickers of renewed energy on the more radical left, from figures such as New York’s Zohran Mamdani and the UK Greens’ Zack Polanski. The question is whether social democrats are willing to break decisively with a failed economic model and to make common cause with those pushing beyond it. Some hope Europe’s far right may yet be weakened by its association with an unpopular US president. But its leaders are already adapting, carefully putting distance between themselves and Washington.

A left capable of uniting around a compelling programme of economic justice – one that redirects anger towards entrenched wealth and power, rather than migrants – remains the most plausible alternative in an era of economic strain and geopolitical instability. It would be overly optimistic to declare that Barcelona heralded its rebirth. But it offered, at least, a glimpse of what it might look like – and a reminder that the slide into rightwing authoritarianism is not inevitable.

• Owen Jones is a Guardian columnist