A local council candidate for the far-right Alternative for Germany (AfD) was attacked with a knife late on Tuesday, the party said on Wednesday.
The politician was injured in the incident, which the German DPA news agency reported happened at about 10:45 p.m. (2045 GMT/UTC) on Tuesday evening.
Police have declined to confirm or deny the incident. They said they would issue a statement later in the day.
DPA reported that the victim had required hospital treatment for cuts and that the perpetrator had been arrested.
The leader of the regional branch of the AfD told the AFP news agency that the candidate was attacked after confronting a person trying to remove an election poster on Tuesday.
"We are shocked and dismayed," said AfD state chairman Markus Frohnmaier.
The alleged incident comes just days after another stabbing attack in the same city when a policeman was killed during a demonstration by the anti-Islamic group Pax Europa.
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rc/ab (AFP, dpa)