The center-left Social Democrats (SPD) had been eagerly settling into their new role as Germany's largest opposition party. They had suffered a bitter defeat at the polls in September's national elections, and party leaders wanted to regroup outside of government. But the failure of exploratory coalition talks between Chancellor Angela Merkel's conservative Christian Democrats (CDU), their Bavarian sister party the Christian Social Union (CSU), the business-friendly Free Democrats (FDP) and the Greens have thrust the SPD back into the spotlight.

Will they once again join Merkel as junior partners in a so-called grand coalition? It is the question SPD members are set to address Thursday at their party conference in Berlin. If they did, they would have a stable parliamentary majority, but many fear that it could also be the beginning of the end of the party.

Coalition conundrum

The SPD has already swallowed that bitter pill twice: They governed with the CDU/CSU from 2005 until 2009 and subsequently lost a huge number of votes during the next national election. Nevertheless, the Social Democrats tried their luck again in 2013, and voters were unforgiving: In this September's national elections, the SPD won 20.5 percent of the vote, the worst electoral showing in the party's 154-year history. It was a shock for the once-proud people's party, which will now be meeting for the first time since the election.

Meanwhile, SPD leader Martin Schulz has partially backed away from his avowed resistance to the idea of once again governing as a junior partner to the conservatives. The move came at the urging of German President Frank-Walter Steinmeier, himself a former leading SPD politician before leaving the party to take up the largely ceremonial role as Germany's head of state. Schulz has recently acknowledged that he is prepared to speak to CDU/CSU party representatives about the possibility. He noted that negotiations will be the determining factor in whether or not the SPD would, in the end, enter a coalition. "There are no predeterminations and nothing is automatic," reads the paper that the party's leader has presented delegates to vote on.

Last stop grand coalition?

The only thing that is certain at this point is that coalition skeptics will not hold their tongues at the party conference. SPD parliamentarian Marco Bülow warned that the party could "risk its very existence" by entering another grand coalition with Merkel. He added that the SPD was sure to lose even more of its members if it did so.

The youth wing of the party, known as the "Jusos" (A German-language shortening of "Young Socialists"), are fundamentally convinced that a new coalition is the wrong path forward: People voted the grand coalition out of office, the CDU and CSU are not reliable partners, the SPD needs all of its energy to renew itself rather than "diving headlong into the next administration."

Whereas the Jusos are trying to drum up support for their position with the Twitter campaign #NoGroKo ("No Grand Coalition"), other Social Democrats see the prospect of such a partnership as a chance to enact important elements of their election program. Lower Saxony State Premier Stephan Weil, who governs there in a coalition with the CDU, says that the SPD cannot be indifferent to whether a government can be formed or not. "There is enough material to create a convincing program for cooperation," he said.

Other Social Democrats are flirting with the idea of a CDU/CSU minority government aided in the Germany's parliament, the Bundestag, by the SPD.

Schulz stands for re-election

Before the party debates arguments for and against joining a new administration, SPD leader Schulz is slated to deliver a highly anticipated speech. Over the last several days, Schulz has repeatedly emphasized that the SPD is well aware of its political obligations but he has also insisted that the party will not be pressured — he is walking a tightrope.

Schulz himself, who will stand for re-election as party leader at the conference, is under enormous pressure. After he was elected to the party's top position with 100 percent of the vote in March of this year, the party took flight in public opinion polls. But a troubled campaign as the SPD's chancellor candidate sent approval ratings crashing back down to earth. Now the party expects Schulz to step up and take responsibility for his role in September's electoral disaster, as well as set a course to help the SPD gather strength and outline a path forward for the future.

Talks next week?

How much confidence will the party's 600 delegates have in him this time around? "I won't get 100 percent again," Schulz admitted with a somewhat pained grin on his face. Still, should the base show overwhelming support and give him a mandate to lead "open-ended negotiations" on joining a new government, he and SPD parliamentary party leader Andrea Nahles plan to meet with leaders from the CDU/CSU as early as next week. Schulz has promised, however, that party members will have the last word on whether the SPD will once again join a grand coalition.