Merz is due to hold a news conference with Markus Soeder, head of the CDU’s Bavarian sister party, the Christian Social Union (CSU), at noon amid speculation they will announce which one of them will be the candidate.

A CDU source told Reuters that it was expected that Soeder would back Merz, 68, an economic liberal who has driven the party to the right since becoming party chief in 2022 after former chancellor Angela Merkel stood down.

Opinion polls have the conservative bloc top in opinion polls, with some even putting it ahead of the combined support for the three parties in Social Democrat chancellor Olaf Scholz’s ruling coalition with the Greens and Free Democrats.

Another possible candidate for the conservative nomination, North Rhine-Westphalia premier Hendrik Wuest, said on Monday he would not join the race and that he backed Merz.

There was no comment from the CDU or CSU.