With one year to go until Germany's federal election, the poll gave Merkel an approval rating of 1.0, down from 1.4 in July on a scale of 5.0 to -5.0. Even more troubling for Europe's most influential politician, she came fourth in a ranking of politicians behind the Green state premier of Baden-Wuerttemberg, Winfried Kretschmann, Social Democrat Foreign Minister Frank-Walter Steinmeier and conservative Finance Minister Wolfgang Schaeuble.

The next electoral test for her conservatives comes in state elections next month in Berlin and Mecklenburg-Vorpommern that are expected to see a strong showing from the anti-immigrant Alternative for Germany (AfD).

The reason for Merkel's poll plunge is familiar: increasingly more Germans blame her for the surge in refugee terrorist attacks over the past month, and her open-door migrant policy has come under intense scrutiny after two attacks claimed by the jihadist militant group Islamic State last month. The poll showed only 44 percent of Germans think her migrant policy is good and 52 percent view it as bad.