But Ms. Kramp-Karrenbauer is widely seen as the chancellor’s favorite. She easily won re-election as governor in March, helping to galvanize her party six months before a federal election.
Already dubbed “Mini-Merkel” by the German news media, Ms. Kramp-Karrenbauer has dismissed the talk of being a queen-in-waiting. Pointing to her cleaning lady act during local carnival festivities, she said she had never been “made for the role of a princess.”
The question of Ms. Merkel’s succession has become a pressing matter five months after inconclusive elections left the chancellor struggling to build a new government. The rapid rise of the far-right Alternative for Germany party, fueled in part by Ms. Merkel’s divisive decision in 2015 to open Germany’s border to hundreds of thousands of people fleeing war and mayhem in the Middle East and Africa, has fragmented the party landscape and made it harder to form a governing coalition.
In Saarland, Ms. Kramp-Karrenbauer has experience leading coalitions with every centrist party there is, from the free-market Free Democrats to the Social Democrats. Her policies and life story offer a mix of liberal, centrist and conservative views with appeal both to voters who like the way Ms. Merkel has modernized their party and to those who hark back to its more socially conservative, Christian roots.
Ms. Kramp-Karrenbauer, a Roman Catholic who married at 22, is the main breadwinner in her family, and her husband stopped working to help raise their three sons.
Even after the chancellor softened her resistance on same-sex marriage, Ms. Kramp-Karrenbauer voiced opposition to the issue.
“Many party members are bemoaning the loss of a more conservative position in the party, and she could be in a position to win back such voters who say the Christian Democrats have become too liberal,” said Marc Debus, a professor of political science at the University of Mannheim.
Weakened by her party’s poorest showing in the election since World War II, Ms. Merkel failed in her first attempt to form a coalition, with the Liberal Party and the Greens. That left her with no choice but to cobble together an agreement with her old partners, the Social Democrats, themselves badly wounded in the election.
The governing deal Ms. Merkel announced three weeks ago, which is subject to the approval of the Social Democratic grass roots, did not go down well with her party base. Three powerful ministries and a string of other concessions went to the Social Democrats.
“We might as well give them the chancellery, too,” complained one conservative lawmaker.
As general secretary, one of Ms. Kramp-Karrenbauer’s first jobs will be to restore calm and discipline in a party deeply divided between those who want to take it further to the right and those who want to pursue Ms. Merkel’s centrist course. She will also be asked to draw up a new party program, which will set the tone for the Christian Democrats for years to come.
Ms. Kramp-Karrenbauer, whose unwieldy name is routinely shortened to A.K.K. in the German news media, caught the chancellor’s eye in 2013, during a previous round of coalition talks, and not only for her negotiating skills: Unlike others who spent breaks scheming and gossiping, she would reportedly pull up a chair, put up her feet and read.
Ms. Merkel has called herself a longtime “admirer” of Ms. Kramp-Karrenbauer. But some argue that seeing her simply as a younger, West-German version of the chancellor, who hails from the former East Germany, sells short a woman admired for her own political acumen.
Ms. Kramp-Karrenbauer had supported Ms. Merkel’s decision to open the border in 2015. But she showed a tougher line in handling the roughly 7,000 refugees who arrived in her state, making it a nationwide example for some.
She had unaccompanied minors arriving without documents undergo medical screenings to help determine their age, and lobbied for Berlin to deport anyone whose application for asylum had been rejected. Male Muslim refugees who refused to accept food from female volunteers should go hungry, she said.
Her positions reflected the mood among her state’s one million inhabitants, said Daniel Kirch, chief political correspondent for the Saarbrücker Zeitung, who has followed her political career.
“She is very attuned to the moods of the people,” Mr. Kirch said. “She reads shifts in public opinion very quickly.”
She also has wide-ranging experience, having entered politics in 2000 as her state’s — and the country’s — first female interior minister. She then moved on to the Education and Labor Ministries, before her election as governor, in 2011.
Frustrated with her coalition partners, the Free Democrats, Ms. Kramp-Karrenbauer let the coalition collapse a year later, calling a snap election that she won. Her next government was with the Social Democrats.
Those experiences could serve her well in Berlin, where she has allies in the conservative women’s union and in Catholic labor organizations but she lacks the extensive network she relied on to govern successfully in Saarland. Analysts say taking a leadership position in the party instead of a ministry will give her the opportunity to build a power base — even if she resisted the idea of moving onto the national political stage for years.
Ms. Kramp-Karrenbauer’s rootedness is what many appreciate in this daughter of a teacher. During carnival last year, she stood on a stage in her home state, dressed as a cleaning lady.
“I just came back from Berlin, where I was given a shift to clean up,” she told the audience in a thick local accent.
The joke drew big laughs at the time, but it proved prescient.