A poll published by the German Spiegel newspaper showed that only 28 percent of SPD voters favoured another grand coalition, though 57 percent of them argued leader Martin Schulz should support a minority government led by Merkel.
"Our continent can't afford to have another four years of German policy on Europe like that practiced by Wolfgang Schaeuble", SPD leader Martin Schulz said, referring to Germany's former finance minister who became unpopular among struggling euro zone states during his eight years in office due to his focus on austerity.
"We must not govern at any price", Schulz said, adding that what was decisive for the SPD playing any role in a new Merkel-led government is that the party can implement its programme. Merkel has said she is "very skeptical" about leading a minority government, which hasn't yet been tried in post-World War II Germany.
In his speech, Schulz listed center-left priorities such as equal treatment for men and women in the labor market and a relatively liberal approach to immigration, rejecting the idea of a cap on the number of refugees allowed into the country. A similar call surfaced in a European Commission reform agenda on Wednesday.
Any EU members who did not agree with this federal constitution should then automatically leave the EU, said Schulz.
Nonetheless, the SPD is holding a three-day congress this week and will ask members' permission to start coalition talks with the Conservatives.