German Chancellor Angela Merkel delivered a moving speech with her Christian Democrats (CDU) in power while she resigned as party leader.
"Our liberal values must be defended, internally and externally," he said.
He mentioned that he was supporting Annegret Kramp-Karrenbauer to succeed him, praising his electoral performance as prime minister of the Saarland.
Kramp-Karrenbauer's main rival in the CDU vote on Friday is the billionaire lawyer Friedrich Merz.
The third candidate, the health minister Jens Spahn, seems to have less chance of winning.
Ms. Merkel's speech was punctuated by applause and obtained a standing ovation of over six minutes at the end. The CDU delegates at the Congress of Hamburg also showed signs with the words "Thank you boss".
Then the conservative party paid tribute to Ms. Merkel, 64, with a video showing the highlights of her 1
In his speech he warned against difficult future challenges, including climate change, maintaining European unity and addressing Brexit.
He reminded the CDU of other electoral successes last year, avoiding mentioning the jokes of this year's arrest in the state elections, which were heavy blows for her.
"I do not need to be president of the party to stay tied to this party And I'm still chancellor," he said.
Emphasizes that the CDU represents human dignity and praised the late US president George Bush Senior and the late German chancellor Helmut Kohl for bringing Germany together in 1990. He was at the funeral of George HW Bush on Tuesday.
Speaking of the end of the Cold War, he told the CDU that "at that decisive moment [Mr Bush] he trusted Chancellor Kohl … he understood how politics should serve everyone".
He expressed "overwhelming gratitude" for playing the role of leader of the CDU. "The future will test our values … we must always approach the work with joy," he said.
Who wants Merkel's work?
Annegret Kramp-Karrenbauer – known as AKK, Merkel's choice
The 56-year-old former Prime Minister of the State of Saarland has been appointed Secretary General of the CDU at the start of this year and is the favorite of the party, suggest the polls. Popular in Saarland and Berlin, it has an unpretentious style and a reputation for calm analysis, as well as political acumen.
His greatest strength is also his greatest weakness; she is a Merkel loyalist, perceived as someone who will replicate much of the chancellor's style and politics.
Friedrich Merz – former leading figure of the party, marginalized by Merkel
The business man millionaire was a powerful player in the CDU in the early 2000s but left politics when he fell with Chancellor.
Since then the 63-year-old lawyer – who has strong ties to America – has built a career in the private sector and works for the US investment company Blackrock. It is aimed at the most conservative and attentive to the party's business and has official support from the former finance minister Wolfgang Schäuble.
Jens Spahn – young and energetic but unlikely to win
The health minister is ambitious and, at 38, the youngest of the three candidates.
Former banker, once described by Mr. Schäuble as "one of the great hopes for the future of our party".
But Mr. Spahn rippled the feathers in the party and in the government. Strongly conservative, Catholic and gay, he is a figure that divides for many.