German Chancellor Friedrich Merz has signalled he is open to reshuffling his government as he seeks to fill the vacancy left by CDU parliamentary leader Jens Spahn, who was asked to step down and eventually resigned on Saturday.

Speaking in ZDF's summer interview, Merz stressed he was speaking "hypothetically", but said he wants a decision on Spahn's successor as leader of the CDU/CSU parliamentary group in Germany's Bundestag by the end of July.

Chancellery Minister Thorsten Frei is widely seen as the frontrunner to replace Spahn, although Merz declined to confirm whether Frei or any other candidate was under consideration.

If Frei were to become parliamentary leader, Merz would also need to appoint a new head of the Chancellery, one of the chancellor's closest aides responsible for coordinating government policy.

The pressure to resolve the issue quickly is also driven by a series of key state elections in September in Saxony-Anhalt, Berlin and Mecklenburg-Western Pomerania. The CDU is facing difficult contests in all three states.