Annegret Kramp-Karrenbauer is a protegee of the chancellor and leader of their conservative Christian Democrats (CDU), but has faced growing doubts over her suitability to replace Merkel, who has led Germany for 15 years but plans to stand down at the next federal election, due in autumn 2021.
Last week, Kramp-Karrenbauer's inability to impose discipline on the conservative Christian Democrats (CDU) in the eastern state of Thuringia dealt a fresh blow to her credibility - already eroded by a series of gaffes.
The regional CDU branch defied her by backing a local leader helped into office by the anti-immigrant Alternative for Germany (AfD), thereby shattering a postwar consensus among established parties on shunning the far-right.
