BERLIN (AP) — German Chancellor Angela Merkel's Christian Democratic Union will elect a new leader at the end of April, party officials said Monday.

Current party chief Annegret Kramp-Karrenbauer had been Merkel's preferred heir-apparent, but announced earlier this month that she would step down and not seek to become the next chancellor in 2021 elections.

The decision came after a series of poor showings in state elections, and a failure by Kramp-Karrenbauer, who is also Germany's defense minister, to establish her authority over the party.

That trend continued on Sunday with state elections in Hamburg, where the CDU saw its support drop by 4.7 percentage points to 11.2% overall, putting the party behind the surging Greens and the Social Democrats.

It was, according to Kramp-Karrenbauer, a "bitter evening."

There are three favorites to succeed her — former parliamentary group leader Friedrich Merz, Armin Laschet, the governor of Germany's most populous state, North Rhine-Westphalia and Health Minister Jens Spahn.

None of the three men has yet officially declared his candidacy. But a fourth candidate, former environment minister Norbert Roettgen, announced last week that he would seek the CDU leadership.

The choice of a new leader will be made at a special party meeting in Berlin on April 25, said Kramp-Karrenbauer.

The Christian Democrats campaign nationally with the Bavarian-only Christian Social Union, and the two parties will together have to decide on a joint candidate to run for chancellor.