http://www.fuen.org/media/146.pdfThis explain why SSW support SPD, it's not so much ideologic agrement with SPD and the Greens, but more the open hostility from CDU.
It should be said that this article put Denmark in better light than it deserve. Denmark treat the German schools in Denmark as every other Free School (private school), which mean that they receive slightly less than public school from the state (85%, which was why the Landtag in Schleswig-Holstein choose that number.), but may raise up to 33% of what the state give among the parents (which they can have a budget of around 113% of a public school per student). Of course the German schools have shown little wish to change that, as it would mean that they would get a smaller budget. The difference in the school system of the two minorities are to large degree based on the German minority in Denmark has traditional been the upper middleclass and upper class, while the Danish minority has traditional been urban workers, rural workers and small farmers, as such they was less able to afford to pay extra for education, as such the Germans was very generous in the Copenhagen-Bonn declaration, which gave the Danish schools this support. Of course it should be said that it was also a attempt to normalise the relationship with the Danish state after the occupation, where Denmark didn't annex South Schleswig after the War, as they had been offered by the allies (and which around 33% of the local population had supported) or deported the German population in Denmark.