By Andreas Rinke and Paul Carrel
BERLIN (Reuters) - Chancellor Angela Merkel's Christian Democrats will convene a special congress on April 25 to pick a new leader, participants at a meeting of top CDU officials said on Monday as they sought to resolve a crisis shaking the party's hold on power.
The meeting took on added urgency after voters handed the CDU its worst result in a state vote in Hamburg on Sunday, punishing it for flirting with the far right in an eastern state and driving it into a messy leadership battle.
The April 25 congress will be held in the German capital Berlin, the participants said.
The CDU succession debate was blown wide open earlier this month when party leader Annegret Kramp-Karrenbauer unexpectedly said she would no longer seek to succeed her mentor Merkel.
Mass-selling daily Bild dubbed the Hamburg result a "debacle" for the CDU, whose faltering leadership has raised questions over the future course of Europe's largest economy.
The CDU slipped into third place in Hamburg, scoring just 11.2% in the northern port city - behind the Social Democrats (SPD), for whom the city is a stronghold, and the Greens.
"The dismal result for Merkel's center-right CDU ... adds to the pressure on the party to resolve the leadership crisis fast," Berenberg bank analyst Holger Schmieding said.
Nationally, the Greens are second, behind Merkel's conservative bloc, and many commentators expect them to have a role in the next federal government.
Merkel, chancellor for almost 15 years, has said she will not run again in the next federal election, due by October 2021.
Kramp-Karrenbauer's decision to give up her ambition of succeeding Merkel came after an eastern branch of the CDU defied the national party and voted with the far-right Alternative for Germany (AfD) to install a state premier from a third party.
That broke a post-World War Two consensus among established parties of shunning the far right.
Kramp-Karrenbauer will brief reporters after Monday's meeting of senior CDU officials and is expected to set out a timetable for a decision on the party chair and possibly the candidate for chancellor.
Four or five candidates are jockeying for the jobs.
A cohabitation arrangement of party chair and chancellor would be harder if erstwhile Merkel rival Friedrich Merz wins the party leadership.
The center-left Social Democrats - junior partners in Merkel's ruling coalition - have signaled they could quit the government if she is forced out as chancellor.
But a powerful caucus of conservatives wants Merkel to stay on until her term ends in October 2021, dismissing calls for her to step down sooner and hand power to the CDU's next leader.