Germany's center-left opposition has won a razor-thin victory in a regional election that is seen as a test for Chancellor Angela Merkel, eight months before nationwide legislative elections.

With most of the votes counted in the northern state of Lower Saxony Sunday, German media reported the opposition Social Democrats and Greens had a one seat majority over Ms. Merkel's center-right coalition.

The election is the last test before September, when polls for Bavaria will take place followed by national elections, which will determine whether Ms. Merkel will win a third term.