Germany’s Social Democratic Party (SPD) chief Andrea Nahles announced she is resigning as well giving up her position as head of its parliamentary group.
She said she took this decision after seeing she did not have the support she needed to lead it.
Nahles announced her resignation following poor results for her party at the European elections.
It remains unclear who will succeed her.
She said she would step down as party leader on Monday and as parliamentary leader on Tuesday.
The announcement follows her party’s poor showing at European parliamentary elections in May, which reduced the SPD to Germany’s third-biggest party behind its senior coalition partner the CDU and the environmental Greens.
The leadership upheaval comes as the Greens have overtaken Chancellor Angela Merkel’s conservatives to become the most popular party in Germany, an opinion poll on Saturday showed, with the SPD support at an all-time low.