German Chancellor Angela Merkel and Social Democratic Party (SPD) leader Martin Schulz. Photo: Reuters / Hannibal Hanschke

The so-called grand coalition between Angela Merkel’s center-right Christian Democrats (CDU) and the center-left Social Democrats (SPD) is looking not-so grand these days.

Merkel and SPD leader Marin Schulz agreed on Friday to open formal negotiations after 25 hours of exploratory talks. But in order just to get to the formal negotiations stage, the terms of the preliminary blueprint must be approved by a special SPD congress next Sunday.

In advance of the vote, SPD party leaders said they are pressing for improvements to the coalition blueprint, Reuters reports, in hopes of winning over rank-and-file party members’ votes.

The party has their work cut out for them. Delegates at a regional SPD party conference in Saxony-Anhalt voted 52-51 on Saturday against pursuing the negotiations with the CDU.

It is unclear what more the SPD can hope to squeeze out of Merkel in order to appease their members. The blueprint reportedly already includes a plethora of promises to appeal to the SPD base, such strengthening the European Union, supporting refugees, and tax and pension expansions.

But the outline for negotiations stops short of including two key SPD campaign promises: tax hikes on the wealthy and the establishment of parity between private and public healthcare plans.

Should the talks fall through, the most likely next option for Merkel would be to call for another round of elections.

The latest impasse comes after Merkel’s failure to broker a separate three-way coalition with two smaller parties. Following huge electoral losses for the CDU, their CSU allies, and the SPD in recent national elections, a repeat of the grand coalition was initially rejected outright by the SPD.