Martin Schulz, the leader of Germany's Social Democratic party, has announced that he will not take up a ministerial post in the next coalition government, despite gaining key roles for his party from Angela Merkel's Christian Democratic Union.
Germany's new Social Democrat leader, Andrea Nahles, shot to national political fame during the fraught days of the last SPD government 15 years ago when, as a left-wing lawmaker, she helped lead a party rebellion against its tough social reforms.
'I hereby declare my decision not to join the federal government and at the same time I sincerely hope that this will end the personnel debates within the SPD, ' Mr Schulz said.
The pitch is created to appeal to his party's 464,000 members before they vote on the deal, which is the final hurdle the SPD needs to pass before the government can be formed.
"We all do politics for the people in this country", he said in a statement, "so it's appropriate that my personal ambitions should take a back seat to the interests of the party".
The head of the Social Democrats' youth wing, who is campaigning against the new coalition, said party members should give up fighting about who does what job and concentrate on debating whether the party enters the government.
SPD leader Martin Schulz drew strong criticism in the party after he announced on Wednesday that he would resign as SPD chairman to become foreign minister, after promising before the election that he would not serve in a Merkel-led government.
German media report that SPD members in the state of North Rhine-Westphalia were especially opposed to Mr Schulz - formerly European Parliament president - becoming foreign minister. A party meeting in January narrowly approved talks with Merkel's Christian Democratic-led bloc, laying bare the divisions. He was already confronted with charges of weak leadership after the result in September's election.
But the final stretch appeared to be more about horse-trading on posts, with the SPD celebrating their advances within the cabinet.
At the top of the party, incumbent foreign minister Sigmar Gabriel - among Germany's most popular politicians - lamented in a newspaper interview "how little respect there is in the SPD in our dealings with one another, and how little someone's word counts for".
Chancellor Angela Merkel's conservatives and Germany's main center-left party are still haggling over a deal to form a new coalition government after negotiations that lasted through the night.