Despite sharing the chancellor's East German past and devotion to democracy, the opposition pick to be Germany's next head of state, Joachim Gauck, is turning out to be Chancellor Angela Merkel's latest threat.

Although the 70-year-old former priest from the gritty port city of Rostock is the underdog in the race for Germany's presidential office, it was his deeply lined face, not that of the chancellor's candidate featured in the nation's most influential news weeklies on Sunday.

Born in 1953, Gauck refused to join the former East German youth organization, he went on to study theology and became a Lutheran pastor. He became a prominent member of the democracy movement against the communists and was elected in 1990 to the last East German parliament.