Germany's Social Democrats (SPD) on Sunday voted to begin coalition talks with Angela Merkel's conservatives in a bid to end the country’s political limbo following inconclusive elections on September 24.

The vote in favor of going ahead with talks, taken at an SPD conference in the former capital, Bonn, attended by some 600 delegates from various state party organizations, came despite considerable rifts within the party.

Of the votes, 362 were in favor of talks compared with 279 against.

The contract that emerges at the end of the coalition negotiations will then be voted on by the SPD's full 440,000-strong membership, which will thus decide whether the so-called "grand coalition" of Germany's main parties is finally established.

Way paved for a Merkel fourth term

DW’s Thomas Sparrow, who was at the conference, said that the mood of excitement was notable, but that the devil would be in the detail of future talks with the conservatives.

"You could clearly sense the tension of the delegates right here," he said. "Delegates have been saying this is only the beginning; that now the SPD has to convince the conservatives and get some success in the negotiations in order to convince the 440,000 members of the Social Democrats who will have the final decisions to have or not to have a grand coalition."

In an appearance on public television, party leader Martin Schulz warned Merkel that there would be "tough negotiations" despite Sunday's "yes" vote.

Merkel has said that she wants to conclude the negotiations by February 12. If they are successful and Merkel receives the necessary absolute majority in the Bundestag to retain her position as chancellor, she could possibly begin her fourth term in office before Easter.

That would mean that half a year had elapsed since the elections – the longest period that Germany has ever remained without a working government.

Too many concessions?

Many SPD members are of the opinion that another four years in governing partnership with the Christian Democrats and their Bavarian sister party, the Christian Social Union, could spell the end of any real individuality for the left-leaning SPD.

Critics of a renewed coalition are also angry at what they see as concessions made by party leader Martin Schulz in exploratory talks with Merkel.

The SPD has already been the junior partner in two "grand coalitions" with Merkel’s conservatives, from 2005 to 2009 and from 2013 onward.

Schulz defends coalition blueprint

In a speech at the congress, Schulz called for the party to remain united, whatever the outcome.

But he also defended the result of preliminary coalition talks, which ended on January 12, saying: "We have achieved a lot and were able to fulfill much that we promised during our election campaign."

Schulz also spoke of the blueprint for coalition talks agreed at the preliminary negotiations as a "manifesto of a European Germany that is conscious of its responsibility for liberty, democracy, cohesion and solidarity in Europe."

Warning on far right

He said French President Emmanuel Macron had told him in a telephone conversation on Saturday that France was afraid that the extreme right could come to power in Germany if the German government did not work with its neighbor to support the European idea.

DW's David Martin, who is attending the congress, said news of the conversation with Macron was met with some disapproval from those SPD members who are not enamored of the French president.

In a call to delegates to vote in favor of coalition talks, Schulz said it would be "negligent" not to take the chance to achieve more social justice in Germany and a restructuring of Europe.

"With all respect for the doubts that many of you have, I ask you to have trust," he said.

Schulz said the SPD could achieve a lot in a 'grand coalition'

Youth wing opposed

But many within the SPD are opposed to the idea of a renewed "grand coalition" — which is being called a "GroKo" in German — under Merkel's leadership, fearing that the center-left party, already faltering in the opinion polls, could be weakened further by such a move.

In particular, the leader of the SPD’s "Young Socialists" (Jusos), Kevin Kühnert, has voiced vigorous opposition, expressing concern that the party has already given too much ground in "exploratory" talks with the CDU/CSU last week.

In his speech, Kühnert said the SPD should risk going into opposition to allow it to gain in strength.

"For now, that means being a dwarf for a while so that we can in the future perhaps be a giant again," he said — an ironic reference to a remark by leading CSU politician Alexander Dobrindt, who had accused the Jusos of carrying out a "dwarves' rebellion."

Kühnert spoke of a 'crisis of trust' within the SPD

Protests outside

Outside Bonn’s World Conference Center, the party conference venue and the old West German parliament, the Jusos were out in numbers as the congress got underway, protesting the notion of another coalition with Merkel’s conservatives. Around 80 to 90 young delegates were set to take part in the vote in the afternoon.

They were competing for noise and exposure with the region’s industrial unions and a large group of migrants calling for greater family reunification rights.

As proceedings began, delegates remained reluctant to say which way they expected the vote to go. All they could hope for was a vote in favor of their side, they said.

Most protesters opposed the idea of a new 'grand coalition' or 'GroKo'

'Voters would think we were crazy'

SPD parliamentary leader Andrea Nahles and the party’s former chief, current acting Foreign Minister Sigmar Gabriel, have also, like Schulz, been trying in the past week to garner support for the 28-page policy paper that emerged from the preliminary talks. The paper is meant to act as a blueprint for the coalition negotiations.

Read more: Germany's 'grand coalition' blueprint: What's in it?

Nahles used her speech at the congress to stress her party's determination to push through its own agenda at coalition talks.

"We will negotiate until the other side starts squealing. And we will get some more good things out of it," she said, adding that if the SPD rejected coalition negotiations, the voters would "think we were crazy."

Nahles: 'Make the other side squeal'

Initial rejection

Following September 24 elections where it garnered just 20.5 percent of the vote — its worst-ever election result — Schulz initially announced that his party rejected any idea of any such further partnership in government.

After talks with the CDU/CSU that ended on January 12, however, the SPD party leadership gave its green light for formal coalition talks, dependent on the result of Sunday’s vote.

The Associated Press, Agence France-Presse, Deutsche Presse-Agentur and Reuters contributed to this report.