Social democracy, the most influential force in European politics for decades, is dying. And the result could be political fragmentation, instability and paralysis.

In recent months, social democratic parties have been swept from power in the Czech Republic, Austria, France and the Netherlands, adding to a long string of losses since 2010.

On Sunday, Italy’s Democratic Party is likely to perform poorly in the national election, finishing behind former Prime Minister Silvio Berlusconi’s right-wing coalition and the anti-establishment 5Star Movement. Among the EU28, that would leave only Malta, Romania, Portugal, Slovakia and Sweden under social democratic leadership.

Meanwhile, the membership of Germany’s once-dominant Social Democratic Party, still reeling from their humiliating collapse in September’s election, is voting on another grand coalition with Angela Merkel’s conservatives.

It’s a “damned if you do, damned if you don’t” decision. Opponents fear the move will only accelerate the party’s decline. Supporters make a similarly dire forecast: A “No” vote would likely trigger a new election and an even more disastrous result.

In some countries, including Germany, social democracy’s demise could lead to de facto one-party rule.

Since World War II, social democracy has stood, along with the center right, as one of the twin pillars of European democracy. Its decline, accompanied by the sharp rise of populists on both the right and left, will likely leave the Continent’s politics neither stable nor predictable.

The center left may survive in some form, but it will likely be shadow of itself. France’s Socialist Party, which won just 6.4 percent in the parliamentary election last year, and Greece’s Pasok, which last polled at just over 6 percent, offer hints of what may lie in store.

In some countries, including Germany, social democracy’s demise could lead to de facto one-party rule, with one dominant party in the center fending off a smattering of smaller ones on the fringes.

The marginalization of social democracy would also have profound repercussions for the EU and its institutions, where the two largest parties have together called the shots for decades in a perpetual, if unofficial, grand coalition.

‘Third way’

The recent flurry of electoral defeats has thrown the movement’s crisis into sharp relief, but a creeping rot has plagued it for some time. Many blame the financial and economic crises that began in 2008 and caught governments flat-footed. But while resistance to austerity fueled social democracy’s decline, the roots of its misfortunes stretch back much further.

“The weakening of the political left has been long in the making,” argued Jan Rovny, a political scientist at Sciences Po in Paris. “It has been largely caused by deep structural and technological change that has altered the face of European societies, changed the economic patterns of the Continent and given a renewed vigor to politics of identity.”

Some believe the era of economic liberalization that followed the fall of the Berlin Wall sowed the seeds of social democracy’s decline.

That was the time of the “Third Way” policies promoted by British Labour’s Tony Blair and the SPD’s Gerhard Schröder, Germany’s Armani-wearing chancellor. The pair were convinced social democracy needed a modern makeover, in particular by becoming more market-friendly. Other European parties followed their lead.

Some viewed the shift not as renewal, but betrayal. After decades of being ensconced in the warm cocoon of Europe’s postwar welfare states, workers found themselves exposed to the cross-winds of global commerce.

Germany, the birthplace of social democracy, exemplified the shift. Schröder’s “Agenda 2010,” a set of reforms that pared back many of the social protections and benefits Germans had come to take for granted, divided the party and cost it the 2005 election.

The SPD hasn’t led the government since. In 1998, the party garnered more than 40 percent of the vote. Last September, it won just 20.5 percent. Much of the SPD’s traditional base has defected to Die Linke, a hard-left movement. “The SPD never overcame the trauma of the Agenda 2010,” said Albrecht von Lucke, a prominent German political scientist and author.

Victim of its own success

Then, as now, the question is what social democracy could have done differently.

Though critics are quick to blame the likes of Schröder and Blair, most economists at the time argued that Europe had become uncompetitive and overburdened by debt. The consensus remedy: economic overhauls and budget cuts.

Few argued that relying on spiraling deficits to fund the welfare state was sustainable. Fewer still saw the inherent dangers in embracing the market.

Put simply, prosperity is killing social democracy.

“People don’t see any major differences between the big parties anymore” — Kevin Kuehnert, SPD

The movement’s founding ideals — a generous welfare state with universal health, education, pensions — have long been realized, helping to lift generations of Europeans out of the proletariat into the middle class. In many countries today, the average social democrat is just as likely to have a white collar as a blue one.

What’s more, technology has forever altered the nature of employment. The days of back-breaking assembly-line work are long gone. And the large industrial labor unions — once social democracy’s core constituency — have faded, leaving the movement’s leaders to chase the prosperous middle class.

As a result, social democracy has lost its raison d’être. In the German campaign, the party struggled to find a central theme, finally settling on the issue of “justice.” To many on the movement’s left, the slogan sounded like mockery.

“People don’t see any major differences between the big parties anymore,” said Kevin Kuehnert, the leader of the SPD’s youth wing, which opposes another grand coalition. “All the parties are pro-European, a bit for protecting the environment and somehow for the status quo. Where’s the hard profile?”

Kuehner and other SPD leftists want the party to do more to champion minimum-wage earners, working single mothers and others at the lower end of the income scale. But at a time of robust economic growth and falling unemployment, that’s a niche audience.

‘A right-wing shift’

And it’s a crowded field. Over the years social democracy’s centrist policies have facilitated the rise of any number of leftist parties, from progressive movements like the Greens to populist groups like Spain’s Podemos, all of which have sucked away voters. That fragmentation is why a lurch to the left by social democracy, like that pursued by Labour under Jeremy Corbyn in the U.K., is unworkable in many countries.

An even bigger threat is the far right. In countries such as France and Austria, social democrats have borne much of the brunt of the populist right’s rise. Social democracy’s support for generous asylum and immigration rules is written into the internationalist movement’s DNA. But it’s a position many of social democracy’s one-time supporters no longer share.

The constant flow of immigrants in recent decades coupled with Europe’s refugee crisis has unnerved many lower-income voters. While some worry about losing their jobs to cheaper workers, others are concerned about the impact the influx will have on their culture and national identity.

Matteo Renzi’s Democratic Party has failed to deliver on its economic promises.

Parties like the France’s National Front and the Alternative for Germany feed on such fears. Social democracy has yet to find a successful strategy to counter such sentiment.

“We’re seeing a right-wing shift for which the left-leaning parties have no answer,” von Lucke said.

The recent success of young, charismatic politicians such as France’s Emmanuel Macron and Austria’s Sebastian Kurz has given rise to hopes among Europe’s social democrats that despite the challenges they face, the right personality could deliver them from their funk.

Matteo Renzi’s record in Italy suggests that’s unlikely. Once celebrated as the future of European social democracy, Renzi’s star has faded.

Renzi won more than 40 percent of the vote in 2014 on a promise to revive Italy’s stagnant economy. Many Italians dreamed of a return to good old days.

It wasn’t to be. His Democratic Party has failed to deliver on its economic promises. While the economy has improved a bit, most Italians aren’t feeling the benefits. The country’s young people are largely shut out of the plugged-up labor market.

Under the watchful eye of the EU and the European Central Bank, the government can’t simply spend — or devalue — its way out of the problem as it often did in the past.

As elsewhere in Europe, frustrated voters in Italy have flocked to the populists. Renzi’s PD is expected to finish in the low 20 percent range on Sunday. It’s chances of playing a role in the next government depend largely upon Silvio Berlusconi’s ability to hoover up enough votes to form a grand coalition.

Nonetheless, some observers argue that the same global tremors that sparked the center left’s crisis could also prove its value as a political force.

“There’s still a role for social democracy in Europe,” insisted Michael Broening, an analyst with Friedrich-Ebert-Stiftung, a foundation supported by Germay’s SPD.

“The problem is that social democratic parties have forgotten how to mobilize.” he added. “Once they manage to rediscover how to do that, there’s still a lot that they can do.”

Madeleine Schwartz contributed reporting.