German Chancellor Angela Merkel will hand over the reins of her Christian Democratic Union Friday after nearly two decades, with the fate of the divided party up for grabs between a loyal deputy and a longtime rival.
The contest's outcome is expected to be crucial in deciding whether Merkel, Europe's most influential leader, can realise her stated goal of completing her fourth term in 2021 and then leaving politics.
Merkel, 64, is quitting the helm of the CDU after a series of poll setbacks rooted in controversy over her liberal refugee policy.
"I hope we emerge from this party conference well-equipped, motivated and united," Merkel said, after accepting a standing ovation from delegates in Hamburg, many holding "Thanks, boss" placards aloft.
"I am confident we will succeed."
Merkel has led Germany since 2005, and moved her party steadily toward the political centre. More generous family leave, an exit from nuclear power and an end to military conscription are among her signature policies.
The two main candidates, CDU general secretary Annegret Kramp-Karrenbauer, known as AKK, and corporate lawyer Friedrich Merz, are locked in a battle over whether to embrace or break with the veteran chancellor's legacy.
A third contender, Health Minister Jens Spahn, 38, an outspoken critic of Merkel's 2015 decision to welcome more than one million asylum seekers to Germany, is running a distant third.
While AKK, 56, is viewed as a keeper of the flame and similar to Merkel with an even temper and middle-of-the-road policies, Merz, 63, has become the torchbearer for those seeking a more decisive break with the chancellor.
"The Merkel era is palpably coming to an end," political journalist and AKK biographer Kristina Dunz said. "Merz could be tempted to see his revenge and lunge for power (as soon as next year)."
This week, Merz -- who has insisted in the face of widespread scepticism that he could work well with Merkel -- won the backing of powerful former finance minister Wolfgang Schaeuble, now the parliamentary speaker.
Both men are seen as harbouring longstanding grudges against the chancellor, after she thwarted Schaeuble's ambition to become German president and Merz's desire to remain CDU parliamentary group leader several years ago.
"Schaeuble's manoeuvre shows: the CDU of the old Germany is trying to make a comeback," news weekly Der Spiegel said.
"It is the CDU of the (former chancellor Helmut) Kohl years, in which men like Schaeuble and Merz barked orders like military officers and women usually made the coffee."
National broadsheet Sueddeutsche Zeitung said Schaeuble's move signalled that the CDU's long-festering divisions, thinly veiled by unity behind Merkel, could well break out in the open after the conference.
"The CDU of the Merkel years is falling apart," it said. "Opposing camps are forming."
Few observers have dared to predict how the 1,001 delegates -- political and party office holders -- will vote.
AKK is believed to have Merkel's strong backing but much will depend on how deep and widespread the longing is for a stronger conservative profile.
Economy Minister Peter Altmaier, a close Merkel ally, criticised Schaeuble's vocal support for Merz as divisive and threw his weight behind AKK as a moderate force who can keep voters from drifting to the extremes.
"Since Wolfgang Schaeuble has now opened the floodgates, I can say that I am convinced that Annegret Kramp-Karrenbauer has the best chance to unite the CDU and win elections," Altmaier told regional newspaper Rheinische Post.
Whoever wins will face towering challenges for the party, which is currently drawing roughly 30 percent at the polls, far below the around 40 percent enjoyed during Merkel's heyday.
It has bled support to the right, in the form of the upstart anti-immigration Alternative for Germany party, and to the resurgent Greens on the left.
Armin Laschet, premier of Germany's most populous state North Rhine-Westphalia, said the CDU needed to begin projecting an image of unity ahead of European elections next May.
"We can't afford another year like 2018 when we fought so much," he told public broadcaster ZDF.