BERLIN (AP) — The center-left state government in one of Germany's biggest regions has lost its majority with the defection of a lawmaker to Chancellor Angela Merkel's conservatives.

A coalition of the center-left Social Democrats and Greens has run Lower Saxony, in northwestern Germany, since 2013. It had a single-seat majority in the state legislature until Green lawmaker Elke Twesten left her caucus Friday.

Twesten said she plans to join Merkel's Christian Democrats. If their caucus accepts her, that would give two center-right parties a one-seat majority — a symbolic boost before a Sept. 24 national election in which Merkel seeks a fourth term.

Lower Saxony is due to hold a state election in January. It wasn't immediately clear whether the conservatives will seek to oust Social Democratic governor Stephan Weil before then.