The battle over the future direction of conservative politics in Germany is in full swing following the decision of Angela Merkel’s would-be successor to withdraw from the leadership of the Christian Democrats.

Annegret Kramp-Karrenbauer’s surprise resignation as CDU leader and potential chancellor candidate on Monday has plunged the country into a period of profound political uncertainty, and left the party faithful heatedly wrangling over whether to continue their centrist course or embrace a tougher form of conservatism in order to win back voters who have drifted to the hard-right Alternative für Deutschland (AfD).

Not only has Kramp-Karrenbauer’s move crushed Merkel’s well-laid-out plans for her own orderly retirement and succession, but it has also laid bare the fractured nature of the conservatives, reflecting similar divisions in traditional parties across Europe.

Although the race to find a successor to Kramp-Karrenbauer has not officially begun, candidates were lining up and had already been in touch with each other, according to German media reports on Tuesday that cited as prime contenders Friedrich Merz, the former leader of the CDU parliamentary group who narrowly lost the leadership contest in December 2018, Jens Spahn, the current health minister, and Armin Laschet, the prime minister of North Rhine-Westphalia.

Markus Söder, the state premier of Bavaria from the CDU’s sister party, the Christian Social Union, has repeatedly said he will not run, despite growing calls among conservatives for him to do so.

A new leader was expected to be chosen by the end of the year, Kramp-Karrenbauer said on Monday, insisting the CDU would be “fit in terms of content, personnel and organisation” for the next scheduled federal elections in 2021. Leading members of the CDU and its coalition partner, the Social Democratic party (SPD), have expressed their concerns that the timetable is too long. The greater the wait, the greater the instability, they argue, amid fears that the AfD will seek to fill the political vacuum.

Neither elections nor an earlier than expected end to Merkel’s term in office have been ruled out, with a growing consensus even among her staunchest supporters that Merkel’s presence is hindering the CDU’s ability to restructure itself. Merkel, who called Kramp-Karrenbauer’s decision, which reportedly also took her by surprise, “regrettable”, is also seen to have been considerably weakened.

At a meeting of high-ranking CDU members on Monday, the most pressing question was how the conservatives should deal with the AfD, to which it has lost millions of voters, amid growing recognition that it is being repeatedly outmanoeuvred by them.

At the heart of its crisis are the differing opinions as to whether it should exclude the AfD or enter talks with it, after CDU politicians in the eastern state of Thuringia ignored long-held party rules last week and voted with the far-right party to oust the state’s popular and respected premier, Bodo Ramelow of the leftwing Die Linke party.

Michael Grosse-Brömer, the first secretary of the CDU’s parliamentary group, sought to allay fears the party was leaning towards either Die Linke on the left, or the AfD on the right. “There’s no wobble either to the left or the right,” he said, arguing the party had good reason to reject cooperation with either party, with both home to members who are under the watch of the domestic intelligence agency for extremist activity.

“Germany is served well neither by a socialist fug nor by rightwing extremists like Björn Höcke,” he said, referring to the AfD’s leader in Thuringia.

Earlier, the CDU premier of Schleswig-Holstein, Daniel Günther, had said Die Linke was “not as bad” as the AfD. That claim was vigorously rejected by Paul Ziemiak, the CDU’s general secretary.

Meanwhile, a poll of German voters suggested almost half – 48% – believed it was inevitable that the AfD, which is already represented in all 16 states and is the main opposition in the Bundestag, will enter government within the next decade, against 29% who thought it was unlikely. Fifty-nine per cent said they did not want to see the AfD in a federal government, against 19% who said they found the idea acceptable, while 26% said its participation in a regional government was acceptable.

Wading into the debate, the former CDU premier of Saxony-Anhalt, Wolfgang Böhmer, warned his party that it ignored the rightwing populists at its peril.

“The AfD has won the support of an astonishingly large number of voters … If my CDU continues to ignore them, they will be pushed into the role of victim,” the 84-year-old told the newspaper group Redaktionsnetzwerk. “We cannot afford to create the impression that the democratic parties are offended because they are not winning the votes.”

Many, both in the CDU and beyond, hold the so-called WerteUnion – or Union of Values – a rightwing conservative grouping within the party, responsible for its current crisis. The group, which has an estimated 4,000 members, formed as an opposition force to Merkel’s centrist course, in particular her decision to allow hundreds of thousands of refugees into Germany in 2015. Unlike the rest of the party, it has not ruled out cooperation with the AfD. Leading members of the CDU have called for WerteUnion members to be excluded from the party.

But Alexander Mitsch, WerteUnion’s chairman, called the group “indispensable” for the CDU. “Without us the party would have no chance of winning any voters any more,” he told the broadcaster SWR.