BERLIN (Reuters) - Germany's troubled Social Democrats (SPD) start choosing a new leader on Monday after Andrea Nahles stepped down, with a membership appalled by plummeting popularity agitating for the party to quit Chancellor Angela Merkel's scrappy coalition.
Nahles, the most vocal backer of the SPD's reluctant decision to form a third grand coalition with Merkel's conservatives, announced she would quit after a disastrous showing at last weekend's European elections.
Voters have punished the SPD for its decision to step in as a coalition partner of last resort with a series of ever more disastrous poll showings, culminating last weekend in the party being toppled in its stronghold city of Bremen after 70 years.
"I believe a coalition walk-out has to come," said Simone Lange, mayor of the northern town of Flensburg, who challenged Nahles for the party leadership at the contest last year.
"The question is when is the right time to do it."
The options facing the party, whose leaders were meeting to start choosing a new leader, are unappealing.
Early elections would likely decimate the party, currently third in the polls behind the surging Greens, but, with the economy slowing, sticking it out until 2021 could see the party plumb even greater depths.
"Crap job for the taking," read the headline in Berlin's left-wing newspaper Die Tageszeitung, highlighting the bind that any successor to Nahles will find him or herself in.
Finance Minister Olaf Scholz, the SPD's most popular politician, told ARD television he would not have time to combine that job with leading the party.
There was more optimism from the conservative camp, with Tobias Hans, a member of Merkel's Christian Democrats and premier of the Saarland region, saying that the government could survive its latest crisis.
"It's not as if this is the first crisis this government has been in," he told German public radio. "Our clear offer to the Social Democrats is: We are available to carry this government through to a good end."
If that fails, options include new elections, an even more unwieldy coalition of three parties, or a minority conservative government propped up on an ad hoc basis. The price of any of these options would likely be an end to Merkel's almost 14-year-old tenure as chancellor.
(Reporting by Thomas Escritt, Editing by William Maclean)