After a week of bickering, Mr Schroder yesterday ordered the Green Environment Minister, Jurgen Trittin, to stop work on his nuclear energy law, legislation that would have authorised the closure of Germany's 19 atomic plants.
Nuclear power is the central plank of the Greens' agenda.
They entered Mr Schroder's government on the condition that the shutdown would begin in the present legislature, although the Social Democrats thwarted attempts to insert closure dates into the voluminous "coalition agreement".
As Mr Trittin acknowledged with some bitterness yesterday, "there are differing interpretations of the agreement".
He has been hurriedly drafting an amendment to the current law which regulates nuclear power, details of which have leaked out.
Alarm bells rang out in the industry and among its friends in government when it transpired that Mr Trittin's amendment would place an immediate ban on reprocessing. German power plants have long-standing contracts with reprocessing facilities in Britain and France and if they were cancelled, it would make the industry liable to huge compensation claims.
At a meeting on Monday, to which Mr Trittin was notinvited, Mr Schroder discussed the matter with leaders of the companies concerned.
The Chancellor reiterated that his government was seeking a consensus and he would only impose a legal solution if, after 12 months of discussions, no agreement was reached.
To Mr Trittin and his colleagues, that was not good enough. "This has been agreed in the coalition agreement," said the Greens' co-leader, Gunda Rostel. "And we as a party expect the SPD to implement the coalition agreement point by point."
Even yesterday, after Mr Schroder's decision was endorsed by the cabinet, made up mostly of Social Democrats, Mr Trittin was sticking to his guns. The dispute must now be resolved by a special session of the two parties' leaders, to be held on 13 January.
The issue of nuclear power has always presented the biggest threat to the coalition and the Greens cannot be seen to cave in any further. Plans for an "ecology tax" have been watered down, and yesterday it emerged that the European Commission was casting a suspicious eye over the package.
The Green cause is not being helped by the presence in the government of a key member of the nuclear lobby.
He is Werner Muller, the Economics Minister, brought into the cabinet at the last minute after the defection of the businessman Jost Stollmann. Mr Muller does not belong to either party, but is a long-standing friend of the Chancellor.
It is already clear that the word of Mr Muller, with no constituency of his own, carries greater weight than Mr Trittin's, whose party represents 6 per cent of the voters. How much more humiliation the Greens can take, nobody knows.Reuse content