Andrea Nahles said on Sunday she would resign as the leader of Germany's Social Democrats (SPD), raising new doubts about the durability of Chancellor Angela Merkel's ruling coalition with the centre-left party.
Merkel's Christian Democrats and the SPD both bled support in last week's European elections as voters turned away from mainstream political parties, eroding support for a ruling coalition that already came close to falling apart last year.
Nahles, whose SPD is a junior coalition partner in Merkel's ruling alliance, said she would resign as party leader on Monday and step down as head of the SPD's parliamentary group on Tuesday.