By Thomas Escritt
BERLIN (Reuters) - A flood of new members signing up to Germany's Social Democrats (SPD) in the hope of voting down a renewed coalition deal with Chancellor Angela Merkel's conservatives is raising time pressure on negotiators trying to thrash out an accord.
The SPD voted on Sunday to begin formal coalition talks with Merkel's bloc despite reservations among some members after the centre-left party suffered its worst result of the postwar era in last September's federal election.
However, the leader of the party's Jusos youth wing, Kevin Kuehnert, spoke out against any re-run of the 'grand coalition' that has ruled Germany since 2013, and he urged more Germans to join the party to help block any final deal.
Party leader Martin Schulz, desperate to win over a sceptical rank-and-file and end Germany's political uncertainty, has pledged to consult the party's 450,000-odd members in a postal ballot before inking any deal.
SPD spokesman Philipp Geiger said on Wednesday the party presidency would meet next Monday to agree rules for the eventual ballot of members on a coalition deal. He denied media reports that the SPD would tighten its voting rules.
In a similar ballot in 2013, people joining the party less than one month before the SPD clinched a coalition agreement with Merkel's party were barred from voting on the deal.
The process of screening individual applications can take three to four weeks, meaning that the hundreds of Germans joining the SPD since Kuehnert's appeal might not get to vote on any new coalition deal if it comes before late March.
JUMP IN APPLICATIONS
Regional party organisations have reported a jump in SPD membership applications, costing from 5 euros a month, since the weekend.
In North Rhine-Westphalia (NRW), Germany's largest state, the SPD had received 600 new applications, in Berlin, 300 and in Lower Saxony, some 400, though they do not all necessarily come from those sharing Kuehnert's opposition to a new coalition.
The numbers are still small compared with the 30,000 who streamed into the party during 2017 amid the initial euphoria that surrounded Schulz's appointment as party leader.
Many in Jusos liken themselves to "Momentum", a left-wing dissident membership group that has influence in Britain's opposition Labour Party, securing the election of outsider Jeremy Corbyn as leader over the objections of the then-leadership.
But SPD leaders warned against a short-term influx of new members joining with just one purpose in mind.
"The SPD isn't eBay," Michael Groschek, the SPD's chief in NRW, told newspaper Die Welt. "We don't put our political decisions up for auction."
(Reporting by Thomas Escritt; Editing by Alison Williams and Gareth Jones)