BERLIN (Reuters) - Chancellor Angela Merkel's heir-apparent pulled out of an election rally on Thursday amid a plagiarism scandal that could cost him credibility, his PhD title, and possibly even his job.
On Wednesday, a newspaper reported Defense Minister Karl-Theodor zu Guttenberg had lifted passages of his law dissertation without correctly attributing them in footnotes or bibliography.
On Thursday, more media outlets came forward with further parts of the thesis which they said were of questionable origin.
An aristocratic politician with a pop-star image, Guttenberg rose to political fame at lightning speed, and had emerged unscathed from a number of setbacks. In a recent poll before the scandal, Guttenberg beat Merkel, still ranking as the country's most popular politician.
This scandal may hit harder.
"This is the first time that there's something out there that could really hurt Guttenberg," Forsa polling institute director Manfred Guellner told Reuters.
Rainer Arnold, Defense policy expert for the opposition Social Democrats in parliament, called for him to step down should the charges prove true.
Guttenberg, who has been tipped as a potential successor to Merkel, has dismissed accusations that he passed others' work off as his own in his doctoral dissertation. He was in Afghanistan earlier on Thursday and made no further comments.
He was meant to speak at a Conservative election rally in Saxony-Anhalt in the evening but canceled after the start of the event, shortly before his scheduled appearance.
Guttenberg wrote his dissertation for the University of Bayreuth in 2006, receiving the top grade of summa cum laude. It was published under the title, "Constitution and Constitutional Treaty: Constitutional developments in the USA and EU."
On Thursday the university said Guttenberg had 14 days to address the allegations with the school. It also denied giving the minister preferential treatment on his dissertation, which he completed while working as a member of parliament.
Guttenberg was recently under fire for his handling of scandals in the military, including the death of a cadet aboard a naval training ship.
Additional reporting by Ayhan Uyanik in Bayreuth, Andreas Rinke and Hans-Edzard Busemann in Berlin; writing by Erik Kirschbaum and Annika Breidthardt; editing by Ralph Boulton