Germany's Social Democratic Party (SPD) signalled yesterday it could quit its coalition with Angela Merkel's conservatives if she is forced out as chancellor - piling pressure on its partner to avoid a snap election as it picks a new leader.
After Ms Merkel's protégée, Annegret Kramp-Karrenbauer, gave up her ambitions for the top job on Monday, the Christian Democratic Union (CDU) is embarking on choosing a new leader and chancellor candidate for the next federal election, due by October 2021.
The possibility of having a rival as party leader while she remains chancellor may be unworkable and force Ms Merkel - who will not seek re-election after leading Europe's biggest economy for around 15 years - to stand down early.
This could trigger an early election, not least because the SPD has made clear its coalition deal is only with Ms Merkel.
SPD general secretary Lars Klingbeil said the party entered the coalition with Merkel "and we will leave the coalition with her, as planned, at the next regular federal election".
"I am aware of no other election date," he added.
The fragile coalition has already come close to collapse several times and the selection last year of two leftists as possible new SPD leaders has left the alliance even more shaky.
Many want to avoid the upheaval of an election during Germany's tenure of the rotating presidency of the EU in the second half of this year.
Mr Klingbeil said he expected the conservatives were aware of their responsibilities and was "not running away from the EU presidency".
The SPD may find it impossible to work with at least two of the potential conservative candidates, Friedrich Merz and Jens Spahn, who are further to the right of the CDU than Mr Merkel.
Ms Kramp-Karrenbauer threw the CDU, and Ms Merkel's plan for a smooth transition of power, into turmoil with her announcement this week, after months of mounting doubts about her suitability.
She said that Europe needs a "capable and stable Germany".
Ms Kramp-Karrenbauer said Ms Merkel and her government were pushing on with preparations for Germany's EU presidency.
"We will start the personnel selection process next week. I have invited those whose names are currently circulating for one-on-one interviews," Ms Kramp-Karrenbauer said.
"At the moment, there are three names circulating in public.
"Whether more come forward, and what gender they are, we will see."
She added that how quickly a successor can be found depends partly on the outcome of her talks next week.