Paris – Soon enough, it seems, the lights will go out at number 10 Rue de Solferino in Paris.

The impressive Left Bank mansion has been the home of the French Socialist Party since the early 1980s.

But, on Tuesday, French newspapers reported that the party, facing a financial as well as political crisis after its disastrous results in this year’s elections, had decided to put it up for sale.

Socialist candidate Benoit Hamon took only 6.4 per cent of April’s presidential vote, starved of support as he was squeezed between charismatic centrist Emmanuel Macron – the eventual winner – and the eloquent radical leftist, Jean-Luc Melenchon.

Now, another European social democratic party failed in the struggle to make an impact.

European social democrats on downward trend

Former European Parliament president Martin Schulz led the German Social Democratic Party (SPD) into Sunday’s general election, but failed to win. Indeed, the SPD slipped to an historic low in terms of support, 20.9 per cent according to initial results.

The party’s polling figures surged after he took over the leadership in January, but they slipped steadily as the election ground on. And it's not just Germany. Elsewhere too, European social democrats are facing disappointing results.

In the Netherlands, the Labour Party (PvdA), previously one of the country’s largest parties, took less than 6 per cent of the vote in this year’s general election, while the more radical Socialist Party gained ground.

The Greek socialist party, PASOK, has dropped to just more than 6 per cent after the country’s fiscal meltdown - following the global financial crisis of 2008 - hit on its watch.

Only four western European countries – Austria, Italy, Portugal and Sweden - now have governments led by social democratic or centre-left parties.

Yet, for decades, these parties were powerful players, frequently dominating governments in many European democracies.

With solid working class support and close ties to trade unions, they helped establish what was often called the European social model, with a market economy, but strong welfare states.

The European centre-left is clearly “on a sharp downward trend,” says political science professor Patrick Diamond of Queen Mary University in London.

“The key question that we don’t know the answer to yet it is whether it’s a cycle or a permanent downward trend,” he says: The movement has bounced back from previous fallow periods, he notes.

What has clearly changed is that these parties are now getting much less than the 30 to 40 per cent of the vote many used to win in the post-war era, Diamond says.

Several factors for the disappointing results

There are both long-term and short-term reasons behind that, he explains.

The traditional working class base of European social democracy has eroded since the 1950s and 1960s.

That said, the changing class structure of European societies and the breakdown of the established party system has hit traditional centre-right parties too. And it's not as if social democratic parties did not enjoy some wins in the late 1990s.

“So I don’t think we can say that these long term trends necessarily preclude social democratic victories,” he argues.

More immediate factors have clearly had a major impact: “The global financial crisis, particularly for those countries where the centre left was in power, such as Britain, was undoubtedly very damaging.”

Parties that were junior coalition partners – such as the PvdA in the Netherlands - have performed “very poorly” as well, Diamond says. Some social democrats argue that the movement’s weakness is also because it has lost its way.

“Social democracy’s whole strength was its ability to be the voice of change and a voice for the poor, the working class, the disenfranchised,” argues Neil Warner, an Irish Labour Party activist and vice president of the Young European Socialists youth movement.

“That was lost when it became a voice of the system ... If social democracy is to have a future it needs to reclaim its ability to be a voice for change and equality.”

In many social democratic parties – perhaps most famously in Britain under Tony Blair and Germany under Gerhard Schroeder – the 1990s and 2000s saw a move towards more market-friendly policies.

That worked at the time, but Warner thinks the time has come to reconsider it.

He points to the relative success of the Portuguese Socialist Party, which has rejected post-crisis austerity measures in government, and the British Labour Party under leftist leader Jeremy Corbyn.

“There’s a real change in class consciousness,” he argues: society is increasingly seen, not as divided between a comfortably-off majority and an impoverished minority, but “more often as 1 per cent versus 99 per cent.”

Diamond is more sceptical: more left-wing programmes have certainly gained electoral traction, he says, but “what’s more questionable is whether ... you can really successfully implement them in government.”