BERLIN (Reuters) - Wary of renewing a coalition with conservative Chancellor Angela Merkel, Germany s Social Democrats are instead contemplating a so-called  cooperation  arrangement that would see them agree on a minimal program but leave contested matters up for debate. With talks on a new government starting on Wednesday, the  cooperation  suggestion is seen by some in the party as an answer to the dilemma of a centre-left party that fears sharing power with conservatives blurs its identity in voters  minds. Social Democrat leader Martin Schulz said he would lead the SPD into opposition after a disastrous showing in September s national election, but was forced to reconsider after Merkel s attempts at forming a three-way government collapsed, leaving Europe s economic powerhouse without a new government. But SPD members and lawmakers are reluctant to sign up for a simple repeat of the four-year Merkel-led grand coalition, after which voters rewarded the junior partner with its worst-ever post-war election result. In a paper seen by Reuters on Tuesday, lawmaker Matthias Miersch, leader of the SPD s parliamentary left caucus, suggested the two parties agree to cooperate on a minimal program while leaving other matters open. The idea, under which the SPD would contribute ministers to a Merkel-led cabinet, would allow the party to support Merkel s conservatives in areas where both parties were in agreement but leave other areas subject to ad hoc haggling between parliamentary parties.  All options were discussed,  said an SPD spokesman of an SPD parliamentary caucus meeting on Monday.  No single model was settled on.  Under Miersch s proposal, the two blocs would agree a common program in areas of broad agreement like house-building, a European investment program and climate policy. They would also agree which party provided which ministry. In some areas, including passing a budget and European and foreign affairs, the parties would agree always to seek a consensus, while in others they would agree to disagree, potentially seeking ad hoc majorities for their own measures from other parliamentary parties. The proposal could help win over party faithful, who must give their blessing to any SPD participation in a future government. But it is far from a done deal, with some of the SPD s own leadership believing early elections were better, party officials said. Merkel s own bloc has been clearer.  I have no interest in half-agreements with the SPD,  said Julia Kloeckner, vice-chair of Merkel s Christian Democrats (CDU).  Either you want to govern or you don t.   Having all the ministerial jobs but no full government responsibilty is cherry picking. You can t be a little bit pregnant,  she tweeted. 