BERLIN: Chancellor Angela Merkel on Wednesday urged the Social Democrats to make the "responsible" choice for Germany as the centre-left party readies for a crucial vote on seeking a coalition with her conservative bloc.
After tortuous negotiations, the parties last week agreed to a coalition agreement in principle but the deal has been thrown into doubt after leading SPD members complained too many concessions were made to Merkel's CDU/CSU alliance.
Some 600 delegates from the SPD will hold a make-or-break vote on Sunday on whether to enter into formal coalition talks -- or risk plunging the country into political chaos.
"I trust that the Social Democrats will make a responsible decision," Merkel told reporters in Berlin.
"I'm not going to interfere but we've all said that we hope for a successful SPD party congress, that is to say an agreement to start coalition negotiations because we believe... that Germany needs a stable government," she said.
Merkel, who is eyeing a fourth term as chancellor, has been struggling to form a government after September's inconclusive election saw mainstream parties haemorrhage votes to the far-right AfD.
Her conservative alliance and the Social Democratic Party scored their worst results in decades, prompting the SPD to vow to go into opposition after two stints as Merkel's junior coalition partner.
But SPD leader Martin Schulz caved to pressure to reconsider after Merkel's efforts to forge a coalition with two smaller parties collapsed in November.
Sunday's vote is expected to be tight after senior party figures savaged the coalition blueprint, which forms the basis for future government policies, saying agreements reached on migration, taxes and healthcare fall short of campaign pledges.
Merkel, whose political life is on the line, defended the hard-fought agreement, which she said was the result of concessions made by all sides.
"We negotiated for a long time to put a fair coalition blueprint on the table," she said.
If the SPD delegates vote against the coalition proposal, Merkel is left with the unappealing option of leading a minority government -- or calling fresh elections.