Despite weeks of turmoil and bitter infighting, the SPD leadership is hopeful its members will back the proposal for a continuation of the current right-left "grand coalition" government, known in German as the "GroKo". "She can win elections and in politics there is only one currency that counts: winning elections". She led the party to its fifth straight state regional victory in March 2017.
By taking on the CDU secretary general role, Kramp-Karrenbauer will build up her network in the party, something she has had only limited ability to do as premier of Saarland, a state of just 1 million people that borders France.
The decision to entrust Kramp-Karrenbauer, also known by her acronym AKK, with bolstering the CDU after it lost ground in an election past year, is significant as some party members are starting to look ahead to a post-Merkel era.
Annegret Kramp-Karrenbauer has been named the new secretary-general of the Christian Democratic Union (CDU), raising speculation that she could eventually replace Angela Merkel as party leader. Her promotion is a slap to CDU critics of the chancellor, though it may make it more likely one of their number will get a cabinet post.
Kramp-Karrenbauer announced her resignation as premier of Saarland, saying that it had not been an easy decision.
Asked what Mrs Kramp-Karrenbauer's appointment means for a succession, Dr Merkel responded: "It's your privilege that you're always three steps ahead of the others". We have our hands full managing the business of the day'.
Morgan Newfield economists say that many senior members of the SPD have reservations about sharing power in a coalition with Merkel and would prefer to rebuild the party after it received the worst results in last year's election since the formation of Germany as a republic in 1949.
Accepting the nomination, Ms Kramp-Karrenbauer promised an overhaul of the party's policies. She would take over from outgoing secretary general Peter Tauber, who is stepping down from the role after a period of illness.
Kramp-Karrenbauer, a close ally of the chancellor, is now minister-president of the southwestern state of Saarland and a member of the CDU's executive committee. Merkel will remain CDU chairwoman.
Mrs Kramp-Karrenbauer said: "We are experiencing one of the most hard periods in the Federal Republic of Germany".
A fluent French speaker, Kramp-Karrenbauer commands respect in the party for her serious, factual approach to policymaking.
Mrs Merkel hopes to be sworn into her fourth term as German leader next month after more than 12 years in office, but there is some pressure from within the CDU to choose her successor.