(CNN)Six hundred delegates from Germany's Social Democratic Party (SPD) will descend on the city of Bonn this Sunday for a special party congress.
'The least bad option:' Germany limps toward a new government
All eyes are on one agenda item: A vote on starting official coalition negotiations with Chancellor Angela Merkel's Christian Democrats (CDU) and their more conservative sister party, the Christian Social Union (CSU).
Just six weeks ago, the SPD voted overwhelmingly to start the initial exploratory talks. This time, it looks to be on a knife edge.
But if the vote passes, the collective sigh of relief is likely to drown out any celebrations.
It's nearly four months since Germany's federal election, in which support for the country's two largest parties slumped leaving Merkel with a mathematical and ideological quandary in her effort to form a new government.
Talks with the liberal FDP (Free Democratic Party) and Green Party collapsed, leaving a renewal of the so-called "GroKo" (Grosse Koalition or Grand Coalition) as the only option -- unless Merkel opts to rule alone in a minority government or put the country on the path to new elections.
"No one is particularly excited about another grand coalition," said Christoph Nguyen, political scientist at Free University Berlin. "But most of the alternatives are even less pleasant to consider."
"It's a bad option, but probably the least bad option."
After leading the SPD to its worst election performance since World War II, Martin Schulz immediately and categorically ruled out a new GroKo.
Voters had called for change, he argued, and the party needed time to regroup and redefine itself in opposition. Launching into a new GroKo would also mean granting the far-right Alternative for Germany (AfD) a set of privileges enjoyed by the largest opposition party -- which Schulz was keen to avoid.
After the FDP walked out of coalition talks two months later, Schulz was quick to stifle rumors of a U-turn.
"I am not available for entering a grand coalition," he said. "It's quite clear that the grand coalition got the red card."
But, under pressure from President Frank-Walter Steinmeier, who urged the country's leading politicians not to rush headlong into new elections, Schulz soon began to change his tune.
Leopold Traugott, policy analyst at think tank Open Europe, thinks he had little choice. "The SPD is stuck between a rock and a hard place," he told CNN.