Chancellor Angela Merkel’s centre-left opponents have won a narrow victory in elections in the German state of Lower Saxony, the BBC reports. The Social Democrats and the Greens won a single-seat majority in the state legislature, a region of eight million people in north-western Germany. The election is seen as a bellwether for national elections in September. The Lower Saxony defeat has set alarm bells ringing for the chancellor, says the BBC’s Steve Evans in Berlin. Mrs Merkel’s CDU coalition has lost a number of state elections as she seeks a third term as Germany’s chancellor. Sunday night’s knife-edge finish saw the SPD and Greens winning a combined 46.3 percent of the vote to the centre right’s 45.9 percent. David McAllister, the incumbent leader of Lower Saxony’s government and close ally of Chancellor Merkel, had been hoping for re-election.The Social Democrats (SPD) enjoyed a comfortable lead over the incumbents in the run-up to the poll, but it evaporated as polling day approached. The SPD leader in Lower Saxony, Stephan Weil, said before the result that a victory in the state polls was a sign that his party would be taken seriously in September’s national elections. Since Mrs Merkel’s re-election as chancellor in 2009, the CDU has suffered setbacks in recent state elections, and has lost power to the SPD and Greens in four other states.