SPD chairman Sigmar Gabriel dismissed the suggestion from The Left's boss Klaus Ernst as "an expression of complete helplessness."
Germany's opposition parties - SPD, the Greens, and The Left party – criticized each other heavily following last Wednesday's missed opportunity to elect an alternative presidential candidate to the post of German president.
Merkel's favoured candidate, Christian Wulff, was only elected after three rounds of voting in the German parliament, and many observers believed that her government could have been forced into early elections if her choice had lost.
Ernst was the first opposition leader to hold out an olive branch to his opposite numbers, saying, "The opposition needs a new beginning too. The government is wobbling, and the opposition is bickering because no-one wants to lead or mediate."
But Thomas Opperman, parliamentary speaker for the SPD, said that Ernst's invitation "should not be taken too seriously." Oppermann claimed that The Left party's decision not to back the SPD and Green party's favoured presidential candidate Joachim Gauck had left it "completely isolated."
Ernst argued that people expected the opposition to show more unity on important questions like welfare cutbacks or health insurance reform. "We have to talk about that," he said.
Gabriel said that The Left party must first clarify whether it is a party of the past – a descendent of the SED, the communist party that ruled East Germany – or a democratic party of the future.
But the SPD boss did indicate his party would be willing to cooperate with a more "pragmatic" Left party in a potential coalition including the Greens. If "democrats, pragmatists, and realists" were to assert themselves in The Left party, Gabriel said, "then there is enough common ground with the SPD for coalition talks on a federal and state level."
Green party headquarters told the Welt am Sonntag newspaper that they had not received an invitation to any summit from The Left, but would consider it if one came. It added that policy talks had taken place between the two parties.