Party chief Sigmar Gabriel is hopeful that European allies such as French President Francois Hollande will give Germany's centre-left Social Democratic Party the electoral boost it desperately needs.
"I'm convinced it will provide us with some gusto for the elections," Gabriel said recently, promising that the birthday celebrations on May 23 in Leipzig, eastern Germany, will be "the biggest international political event in Germany this year."
With four months to go before the September 22 elections, the SPD's standing in the opinion polls is currently stuck at around 23 percent. That is way below the current score of 40 percent by Chancellor Angela Merkel and her conservative CDU party with its Bavarian sister the CSU.
Merkel can seemingly do no wrong in her handling of the euro crisis, but the SPD's chancellor candidate Peer Steinbrueck could hardly be less popular.
If the Social Democrats have backed Merkel in all of the eurozone rescue packages since the start of the crisis, they have nevertheless never hesitated to criticise her austerity policies. Leipzig looks set to provide them with an ideal forum for this.
One of the highlights of the festivities there will be a speech by Francois Hollande, even if the French president, too, has seen his popularity slump to a new low.
Merkel, too, will be at the party, but will not give a speech, while German President Joachim Gauck will.
No meeting is planned between the German and French leaders on the sidelines of the festivities. But the two will have participated the day before in an EU summit dedicated to fiscal policy and growth.
Among the other invited guests will be the heads of all Socialist and Social Democrat parties across Europe, including Austrian Chancellor Werner Faymann and Norwegian Prime Minister Jens Stoltenberg.
It was on May 23 1863 that the General German Workers' Association or ADAV - the predecessor to the SPD - was set up in Leipzig by the pioneer of German socialism, Ferdinand Lassalle.
And the celebrations in Leipzig will allow the Social Democrats to recall some of their greatest achievements, such as the resistance to Nazism.
However, analysts believe the impact of the celebrations on German voters will be limited.
"Above all, it will be an opportunity to mobilise the SPD membership for the elections," said Jens Walther, political scientist at the University of Düsseldorf.
And Walther suggested the presence of Merkel could actually backfire on the Social Democrats as it might conjure up images of a possible grand coalition between the two main parties after the elections.
"And that is something the SPD must avoid at all costs if it wants to win votes," the expert said.
At the centenary celebrations in Hannover in 1963, the then conservative chancellor Konrad Adenauer refused to attend.
With the heads of all socialist parties assembled in Leipzig on Wednesday evening, they could agree on a joint candidate for the post of European Commission president, suggested SPD chief Sigmar Gabriel.
The name of German Social Democrat Martin Schulz, president of the European parliament, has often been mooted in the press as a possible successor to Portugal's Jose Manuel Barroso.
The same day, leaders of the left are scheduled to set up a Progressive Alliance in Leipzig, a sort of platform of ideas wider than the current Socialist International. The SPD is no friend of the latter and has considerably scaled back its contribution to it since it was set up in Paris in 1889.
"The new 'Progressive Alliance' network is complementary to efforts to reform the Socialist International. It should be an organisation which complements the SI, not replaces it," the leadership of the French Socialists insists.