Angela Merkel’s political future looked uncertain on Sunday as her coalition government suffered heavy losses in key regional elections for the second time in as many weeks.

Mrs Merkel’s Christian Democrat party (CDU) plunged to its worst result since 1966 in the state of Hesse, according to initial exit polls. Home to the German financial capital, Frankfurt, the state is a major symbolic prize and has been a CDU stronghold for decades.

But in a vote widely seen as a verdict on Mrs Merkel’s troubled national government, her main coalition partners, the centre-Left Social Democrats (SPD), suffered major losses too and were in danger of their worst ever postwar showing in the state.

The main beneficiaries…