BERLIN (Reuters) - The coalition deal forming the basis of Germany's ruling alliance is not up for renegotiation and the new leaders of the Social Democrats (SDP) must decide whether or not they want to stay in government, Chancellor Angela Merkel's protegee said on Monday.
The coalition's future looks shaky after the election of new SDP leaders who are demanding a shift in policies that their conservative senior partners are resisting.
Annegret Kramp-Karrenbauer, chairwoman of Merkel's Christian Democrats (CDU) and would-be successor as chancellor, said the election of the new SPD leadership was not sufficient grounds to change the ruling parties' coalition agreement.
"So the new SPD leadership must decide whether they want to stay in this coalition or not," she told broadcaster ZDF.
"We have a coalition and this coalition has a coalition agreement. That is the basis on which we are working. And it applies for the whole legislative period. We are not a therapy facility for the respective coalition, government parties."
Two strong leftist critics of the coalition with Merkel's conservatives - Norbert Walter-Borjans and Saskia Esken - won a vote for leadership of the SPD on Saturday, putting Europe's largest economy at a political crossroads.
Their ascendancy raises the chances of an early election or minority government if the SPD leaves the coalition, which could trigger instability at a time when the far-right Alternative for Germany (AfD) is the third largest party.
Attention will shift quickly to an SPD conference starting on Dec. 6, at which delegates are set to approve the new leadership and also vote on a yet-to-be published motion on the coalition.
Malu Dreyer, who has been acting as interim SPD leader, sought to quell speculation about the future of the coalition.
"I think we should calm down a bit," she told ZDF.
"We should take note that the party has elected a new leadership - that is the point - and it will set out its priorities on the question of how we proceed with the grand coalition, but we will discuss that in a few days at the party conference."
(Reporting by Christian Goetz and Paul Carrel; Editing by Andrew Cawthorne)