Angela Merkel’s chosen successor came under intense pressure on Monday after disastrous regional election results saw her party suffer crushing losses to the nationalist Alternative for Germany party (AfD).

Annegret Kramp-Karrenbauer was forced to defend her leadership after the AfD forces her Christian Democrat party (CDU) into a humiliating third place in the eastern state of Thuringia.

Popularly known as AKK, Ms Kramp-Karrenbauer took over as party leader from Mrs Merkel last year and was widely expected to succeed her as chancellor.

But following a string of disappointing election results, questions are growing in the CDU over whether she can be trusted to lead the party into a general election.

Ms Kramp-Karrenbauer faced the party at a stormy meeting in Berlin on Monday, at which she was forced to defend her hopes of standing as its candidate for chancellor in 2021.

“The leadership issue must be resolved now,” Tilman Kuban, the head of the CDU youth wing, reportedly told the meeting.

But Ms Kramp-Karrenbauer insisted the candidacy would be decided in 2020. “I have been elected leader. If anyone wants to resolve it sooner they should say so and challenge for the leadership at the party conference in three weeks.”

Her words were greeted with applause, but there is no mistaking the fact that rivals are circling her.

“The CDU can no longer ignore the election results from Thuringia or just sit them out,” Friedrich Merz, the man she narrowly beat to the party leadership last year, tweeted in a clear warning shot.

Ms Kramp-Karrenbauer has now presided over heavy losses in the European elections and regional elections in three German states.

Following previous losses, she moved into the cabinet as defence minister in an attempt to shore up her position.

But she came under fire in the run-up to the Thuringia election for getting involved in a damaging cabinet row over Syria policy with Heiko Maas, the foreign minister.

“These sort of state election results are not disconnected from what’s happening at a national level,” Reiner Haseloff, a senior CDU figure, told German television.

Mike Mohring, the CDU regional leader in Thuringia, lost no time in blaming AKK for the debacle. “Berlin was not helpful in the weeks leading up to the election,” he said.

The CDU leadership has agreed to Mr Mohring’s demand to be allowed to open coalition talks with the Left Party in Thuringia.

The CDU has previously always refused to consider any coalition with the AfD or the Left Party.

But the two parties dominated the Thuringian election results and no coalition is possible without one of them.

The Left Party, a successor to the former East German Communist Party, came first in the state with 31 per cent.

Mr Mohring contends it is the lesser of two evils compared to the AfD, whose lead candidate in the state, Björn Höcke, has been compared to Hitler by German national television.