German Chancellor Angela Merkel on Sunday expressed full support for Armin Laschet, her would-be successor, during a visit to Germany's flood zone.

Laschet, the head of Merkel's Christian Democrats (CDU), was long the favorite to replace her as chancellor after elections on September 26, but his ratings have plummeted following a series of gaffes.

Merkel defended him during a visit to the city of Hagen on Sunday, telling reporters he was "leading the largest state in Germany very successfully."

"Anyone who can lead a state like this can also lead Germany as chancellor," Merkel said after visiting local officials leading the reconstruction effort.

(With input from AFP)