The embattled leader of Germany’s ruling Christian Democrats has challenged delegates at the party’s conference to back her vision or else “end it here and now”, amid deep divisions over the future direction of the party.

Annegret Kramp-Karrenbauer told the CDU’s annual conference in Leipzig she was putting her future on the line in response to stinging criticism over her leadership style.

The 57-year-old, who took over as CDU head from Angela Merkel almost a year ago, shocked party members towards the end of a rousing 90-minute speech by inviting them to move to vote her out if they wanted to.

“If you want, let’s get this out into the open today. Let’s lay it to rest, here, now and today,” she said. “But if you’re of the opinion that we should embark on this road together, let’s roll up our sleeves and get on with it.”

Most of the 1,000 participants gave her a standing ovation, applauding for seven minutes.

Saxony’s state leader, Michael Kretschmer, who is hosting the congress, told delegates the applause was a signal that Kramp-Karrenbauer had the backing of the party. “Today is not the end, Annegret,” he said. “Today is when we really get going.”

Facebook Twitter Pinterest Kramp-Karrenbauer with Merkel at the conference. Photograph: Matthias Rietschel/Reuters

The 74-year-old party is reeling from recent poll disasters, and low public approval ratings for Kramp-Karrenbauer. It has lost millions of voters to the rightwing populist Alternative für Deutschland as well as to the Greens. Its share of the vote in polls for the Bundestag, which is currently home to seven parties, is hovering at around 30% – a paltry figure compared to the results it was used to.

It is also struggling to agree on the direction it should take once Merkel’s term as German chancellor ends. Merkel announced last year that she was stepping down as CDU leader after 18 years and would not stand as chancellor again after her fourth and current term, which is due to end in 2021.

Kramp-Karrenbauer admitted the party had had a “difficult year” following historically poor showings in state polls in Saxony, Brandenburg and Thuringia as well as in the European Union parliamentary elections. But in a dig at her arch-rival, Friedrich Merz, who called Merkel’s government “abysmal” and has led the calls for the party to shift from the centre to the right, she said the tendency within the party to criticise its own members in the government was self-defeatist and “not a good campaigning strategy”.

Addressing delegates after Kramp-Karrenbauer, Merz did not, as had been widely expected, continue his criticism of the government. He instead thanked Kramp-Karrenbauer for a “combative, courageous and forward-looking speech” and said the years of CDU-led governments had been “good years for Germany”. He said he was happy to take part in reshaping the CDU “if you want me”.

But Merz supporters speaking on the conference sidelines said if Merkel’s grand coalition broke up, Merz would be waiting in the wings. One of his staunchest backers, Christian von Stetten, said before the conference that “the party’s future direction will not just be left to Kramp-Karrenbauer”.

Kramp-Karrenbauer has been seen as Merkel’s successor, sometimes even referred to as “mini Merkel” since she was narrowly elected party leader last December. She was subsequently appointed as defence minister and has drawn both praise and criticism for pushing for Germany to play a stronger role on the international stage.

Among the issues due to be discussed at the two-day conference are digitalisation, including whether the Chinese firm Huawei should participate in the future of its 5G network, a proposal to ban headscarfs for young girls, the introduction of a basic pension and whether the German flag should be flown outside schools.

While Merkel’s presence will continue to loom large in the party as long as she remains chancellor, her role at the conference is low-key for the first time since 2000. In an opening speech she defended the work of her coalition government but reiterated that she would not interfere in the question of where the party chose to go.