German Chancellor Angela Merkel suffered a major political blow less than eight months before elections when her education minister, a close ally, stepped down on Saturday over plagiarism allegations.
Merkel said she had accepted the resignation of Annette Schavan "with a heavy heart" after her former university stripped her of her doctorate, saying she had plagiarised parts of her thesis "Person and Conscience" 33 years ago.
Schavan vowed to fight the allegations but said she did not want the scandal to damage the office, the party or the federal government.
"I think today is the right day to leave my ministerial post and to concentrate on my duties as a member of parliament," said an emotional Schavan.
Merkel said she had suggested to the country's president that Johanna Wanka, a minister in the state of Lower Saxony, should succeed her.
Schavan, 57, became the second close ally of Merkel to step down over plagiarism after Karl-Theodor zu Guttenberg, a popular defence minister sometimes tipped as a future chancellor, resigned in 2011.
The extent of Schavan's alleged plagiarism is thought to be less than that of zu Guttenberg's, whose actions earned the aristocrat the nicknames "Baron Cut-And-Paste" and "zu Googleberg".
Nevertheless, Schavan's mistakes were seen as indefensible given her position as education and research minister in a country where academic titles are taken extremely seriously.
There was also an element of schadenfreude given her reaction to zu Guttenberg's downfall, when she said she was "ashamed" of her former cabinet colleague.
"As someone who was herself awarded a doctorate 31 years ago and who has supervised several doctoral candidates, I am ashamed and not just behind closed doors," she told the Sueddeutsche Zeitung at the time.
Merkel paid tribute to Schavan, seen as a close personal friend as well as a strong political ally, saying: "Her performance in this very important post has been extraordinary. Education and research in Germany... owe a lot to her."
"She has put her own personal interests behind the interests of the greater good," said Merkel, visibly shaken.
Mass circulation daily Bild noted: "The departure was difficult for both of them ... the chancellor has seldom seemed so moved as in these few minutes. Her eyes seemed to be welling up."
Schavan thanked her "dear Angela" and said their friendship would extend beyond this professional break.
"I will not accept this decision (from the university) and will fight against it. I neither copied my dissertation nor cheated. The accusations... affect me deeply," said Schavan.
However, she acknowledged that there were consequences to be drawn when an education and research minister takes up a legal battle with her former university and said she was resigning as "the office should not be damaged."
"My decision stems from the same responsibility with which I have tried to carry out my office," she added.
"First my country, then my party and then me personally."
The resignation came as an unwelcome distraction for Merkel as she gears up to run for a third term at the helm of Europe's top economy in elections on September 22.
Although the chancellor enjoys a huge popularity lead over her gaffe-prone Social Democrat rival, Peer Steinbrueck, the gap between the two main parties appears to be narrowing, according to some polls.
A survey for ARD public television channel on Friday showed Merkel's conservative Christian Democrat/Christian Social Union bloc losing a point and Steinbrueck's SPD gaining two points to close the gap to 10 points.
Writing before the resignation, the influential weekly Die Zeit noted that Merkel could always re-employ her friend after the election if she won her legal scrap with the university.
"After the conclusion of the process in the autumn she could then even re-install her in office -- provided that Schavan wins her legal battle and Merkel the election," wrote the paper.