Angela Merkel is stepping down as party leader but hopes to see out her term as Chancellor. Photo / AP
German politics is a realm where predictability is prized. But as the grandees and the grunts of Germany's dominant post-war party gather in Hamburg today, they face an uncertainty unknown for the past 18 years.
The Christian Democratic Union is to elect its first new chief since a 45-year-old east German physicist named Angela Merkel took charge in 2000. The choice is between a close Merkel ally who wants to carry on with the big-tent centrism the Chancellor has long championed, or a longtime rival who aims to steer the party back to the right.
Whoever wins becomes the favourite to take over as Germany's next leader, with the opportunity to shape Europe's primo political and economic player for years to come. That means that while Merkel is nowhere on the ballot in today's vote, she has everything at stake.
"It's about her legacy," said Robin Alexander, a German author and journalist who has written extensively on the Chancellor. "If Merz wins, it means the CDU wants something new. If AKK wins, they want to continue and still value her. Merkel is heavily invested in AKK."
Merz is Friedrich Merz, a 63-year-old corporate lawyer who has been out of politics for nearly a decade after being unceremoniously sidelined early in Merkel's reign. AKK is Annegret Kramp-Karrenbauer, a quietly effective 56-year-old politician whom Merkel tapped to be CDU general secretary this year after a long tenure leading the tiny west German state of Saarland.
In addition to being a stylistic soulmate, Kramp-Karrenbauer would give Merkel the chance at a graceful exit from the chancellery. Merkel has said she intends to govern until her term is up in 2021, and the selection of Kramp-Karrenbauer would make that at least a possibility.
A hastier departure is likely should the CDU go with Merz. Not only would the vote signal a repudiation of Merkel, but it would also create an unwieldy dynamic in which two people who are known not to get along sit together atop the German political world.
Polls show Kramp-Karrenbauer is better liked than Merz among CDU voters and the public at large. But Merz has received a notably more enthusiastic response at a series of town-hall-style meetings held across the country in the weeks since Merkel stunned the German political world by announcing she would step aside as party chair.
Ultimately, the choice is up to the 1001 delegates who are convening in Hamburg, a mix of party elders and local office-holders who will make a decision with consequences for 83 million Germans.
The party's choice mirrors one faced by centre-right parties across Europe as they attempt to adapt to a surging far-right. In countries such as Austria, France and Britain, the traditional conservative heavyweights have adopted much of the rhetoric and positioning of their populist rivals. The strategy has succeeded in some places and failed in others.
Merkel, while toughening her stance on immigration, has largely declined to try to beat the far-right by matching its approach to politics. She refuses to co-operate with the anti-immigrant Alternative for Germany (AfD), and continues to defend the decision that more than any other made her a pariah among the insurgent party's followers: Her 2015 choice to keep German borders open amid an unparalleled influx of asylum-seekers.
That stance has won her plaudits as a beacon of tolerance and humanitarianism who is prepared to face down a rising tide of populism in defence of Western values.
But it has also earned her scorn from not only the AfD, but also from some within her own party who feel the CDU has strayed too far to the centre - or even the left - under her leadership.
Most of those disaffected CDU voters are pinning their hopes on Merz. During his years in the political wilderness, as he grew wealthy in the business world, he was known to be critical of Merkel's inclination to stray from conservative stands. That tendency included not only her handling of refugees, but also the introduction of a minimum wage, an end to nuclear power and a bolstering of the social welfare system.
As a candidate, Merz has been careful not to portray himself as a zealous adversary of Merkel's, mindful of the fact that she still enjoys wide appreciation in the party for her 13-year run as Chancellor. But he has done just enough to signal that he would take the CDU - and, perhaps, Germany - in a different direction.
But the CDU has not only lost voters to the right. Centrist and progressive voters have also abandoned the party, prompting a surge for the environmentalist Greens. That's one reason why many in the CDU are wary of a lurch to the right and favour a less polarising candidate.
Much like Merkel, Kramp-Karrenbauer is known as a moderate consensus-builder who eschews ideology in favour of pragmatism.
She, like the Chancellor, has encouraged the country to move on from an endless debate over decisions made in 2015. The similarities have earned her the moniker "mini-Merkel".