TEHRAN, Young Journalists Club (YJC) - Andrea Nahles said she wanted "clarity" after questions were raised about her ability to lead the party.
"The necessary support for me to carry out my duties isn't there anymore," she said in a statement Sunday.
Nahles said she will be stepping down from her post as chairwoman of the Social Democrats and leader of its parliamentary faction in the coming days, to ensure that her successors are found "in an orderly fashion."
The Social Democrats fell to third place behind Merkel's center-right Union bloc and the Greens in the May 26 European Parliament election in Germany.
Nahles took over as party leader in February 2018, as the Social Democrats reluctantly extended their "grand coalition" with Merkel's conservatives following a poor showing in the previous year's German election.
While the Social Democrats have managed to push through their agenda of improving social welfare and working conditions for millions of Germans, voters haven't rewarded the party for it in the polls.
Source: AP