Peer Steinbrück, a former German finance minister, is to run against Chancellor Angela Merkel in elections next year. The outspoken and quick-witted centrist is not free from controversy within his own party.

Oozing northern German coolness, sometimes abrasive and impatient, a man with lots of irony and biting sarcasm - that's how 65-year-old Peer Steinbrück is often described.