Angela Merkel’s Christian Democratic Union (CDU) is to elect a new leader at the end of April, its current head has announced.

Annegret Kramp-Karrenbauer, known as AKK, had been the chancellor’s preferred successor, but recently said she would step down and not seek to replace Merkel in elections next year.

The new leader will be chosen at a special party meeting in Berlin on April 25, AKK said.

The party has performed poorly in state elections, most recently in Hamburg on Sunday which saw the CDU finish in third place and record its lowest ever score at just over 11%, down more than 4.5% from the 2015 ballot.

AKK said she would quit following a regional election scandal, in which a long tradition among the German political mainstream of shunning the far right was broken.

AKK’s authority was challenged when the CDU in the eastern state of Thuringia appeared to coordinate with the Alternative for Germany (AfD) party in electing a marginal figure to be state premier, in order to oust the left-wing incumbent.

"This is a party that's currently in a leadership crisis": Euronews correspondent Jessica Saltz reports for Euronews Now in the video player above.

There are three favourites to succeed Kramp-Karrenbauer: former CDU parliamentary group leader Freidrich Merz, North Rhine-Westphalia governor Armin Laschet, and Health Minister Jens Spahn.

None has yet officially declared his candidacy but a fourth contender – former environment minister Norbert Roettgen – said last week that he would run.

The Christian Democrats and their Bavarian partners the Christian Social Union (CSU) campaign nationally together and will have to decide on a joint candidate to run for chancellor in 2021.

Angela Merkel has said she will not stand again, after nearly 15 years as chancellor.