By Andrea Shalal
BERLIN (Reuters) - German conservatives narrowly favour Angela Merkel's protege to succeed her as Christian Democrat (CDU) leader, a poll showed, as rivals for the position promised to back the chancellor through her fourth term if they win.
Some 35 percent of supporters of the conservative bloc that also includes the Bavarian Christian Social Union (CSU) said they backed Annegret Kramp-Karrenbauer to take over the CDU helm, Friday's survey for broadcaster ZDF showed.
Businessman Friedrich Merz scored 33 percent and Health Minister Jens Spahn 7 percent.
CDU delegates will elect a new leader at a party congress in December, but views among the larger conservative bloc are likely to shape how they vote. Whoever wins is expected to become the CDU's candidate for chancellor at the next national election in 2021.
While stepping down as CDU leader, Merkel has said she plans to serve her fourth term in full, though there has been speculation that she might leave early if Merz or Spahn won the party leadership.
Merz, who stands to the right of Merkel on the CDU spectrum, called the chancellor to assure her of his support and cooperation if he won, Der Spiegel reported on Friday.
The businessman, who dropped out of politics after clashing with Merkel, repeated that message during a meeting with CDU lawmakers in Berlin on Thursday, the magazine said.
Merz is chairman of the German arm of BlackRock, whose Munich offices prosecutors searched on Tuesday as part of Germany's largest post-war fraud investigation. It covers the period 2007-2011, before Merz joined the hedge fund.
Spahn offered similar assurances in an interview with the Funke newspaper chain published Friday. "As party leader, I would work with her in as trusting a manner as before," he said.
Asked if Merkel should remain chancellor for the next three years, Spahn said, "Why not?"
Kramp-Karrenbauer told the Frankfurter Allgemeine Zeitung newspaper that Merkel had not signalled any intention to step down as chancellor.
The poll for ZDF, in which Mannheim-based Forschungsgruppe Wahlen questioned 1,200 people, said some 63 percent were happy with Merkel remaining as chancellor until 2021, while 34 percent were not.
(Reporting by Michelle Martin and Andrea Shalal; Editing by Joseph Nasr and John Stonestreet)