"We are strong," SPD leader Sigmar Gabriel said, raising his fist as he introduced Peer Steinbrück to the podium at the party's headquarters in Berlin's district of Kreuzberg on Sunday evening.
Steinbrück smiled with characteristic firmness as he praised his party's "dialogue-directed" campaign and thanked those that had supported him.
He was, however, quick to return to the defensive. "To those who accused us of running a campaign short of content," he said, "Let me contradict you."
“We talked to people about politics and the people wanted to talk about politics.” he said.
But Steinbrück refused to speculate about how the next German government might look. "We should not jump to premature conclusions,” Steinbrück said, referring to the result – which theoretically leaves open several possible governments.
Steinbrück has repeatedly ruled out going into government with the Left Party. However he was also been non-committal about joining Merkel's Christian Democrats (CDU) in a so-called “grand coalition.”
“We'll stick to our policies,” he promised, emphasizing the party's important role as a strong opposition to Merkel's CDU.
And that seemed to be how SPD supporters at the Willy-Brandt-House wanted things to stay. There was little support for a “grand coalition” with the Christian Democrats.
“Anything would be better than a grand coalition,” SPD supporter Felix Beyer told The Local. “It would be a betrayal for voters and party members ... They voted for a red-green coalition, not a government with the Christian Democrats ... Let's send the Greens forward.”
SPD supporter Marc Zechnel agreed. “In general I'm sceptical about it … If they find enough common ground it could work but on the whole, I think it could do more harm than good.”
Other supporters believe Steinbrück's decision not to govern with the Left Party was premature. “Red, red, green would be the best option,” [Social Democrats, The Left Party and The Greens] Angela Emdahl told The Local. “The Left party has succeeded in speaking to a demographic that feels neglected by the SPD.”
Having been accused of failing to distinguish itself from its powerful rivals, the Social Democrats look set to play it tough in possible negotiations towards a grand coalition.
Among the issues likely to be top of the agenda is the introduction of a nationwide minimum wage which the Social Democrats have pledged to set at €8.50 an hour. Another issue the party is likely to stay firm on is allowing people of migrant background to have dual citizenship.
The atmosphere at the party's headquarters on Sunday was low-key and calm. Supporters enjoyed a coffee at 'Willy's cafe' - a tribute to former Social Democrat chancellor Willy Brandt - and drank their Pilsners in moderation.
It was difficult to assess whether the dominant feeling was resignation - that the party would end up co-operating with the Christian Democrats - or relief that it had not slid yet further down the polls.
One thing however is clear. Whether the SDP become Merkel's partners or stay put on the opposition benches, they're determined not to make the next four years easy for the chancellor. And they must also find a way to reverse their slow decline in share of the vote and party membership.