The new leader will be chosen by a vote among 400,000 CDU members before being formally elected at a congress on January 21 and 22 in Hanover, outgoing party chief Armin Laschet and general secretary Paul Ziemiak told a press conference in Berlin.
Previous leaders have been elected by a much smaller number of delegates at a party congress.
Laschet said it was “a good way to get the CDU off to a new start” after the party and the Bavarian CSU scored their worst election result since World War II in September’s vote.
The Social Democrats (SPD), who emerged as the biggest party, are in talks with the Greens and the liberal FDP to form a ruling coalition and hope to have a new government in place by early December.
No candidates have yet put themselves forward for the CDU leadership, but Friedrich Merz and Norbert Roettgen – who both ran against Laschet when he was elected party leader in early 2021 – are among those expected to run.
Merz is a veteran right-winger and longtime arch-rival of Merkel, while Roettgen is a foreign policy expert who sits nearer the centre of the party.
Health Minister Jens Spahn, who ran unsuccessfully for the leadership in 2018, is also thought to be a possible contender.
Merkel stood down as CDU leader in 2018 after a poor election performance for the party in the state of Hesse, but vowed to stay on as chancellor until 2021’s general election.
After 16 years in power, she will continue as acting chancellor until a new government is formed.