The stereotypes were all present and correct: Kiel's main sports arena was a sea of side-partings, tucked-in shirts, blazers-and-jeans combos, and the cavernous hall rang with appeals to Christian values and exhortations against abortion and cannabis. The people of this German port city could have no doubt that the youth wing of Angela Merkel's Christian Democratic Union (CDU), the Junge Union (JU), had descended on them this weekend for their annual convention.

It was always going to be a tough crowd for the chancellor, who is facing possibly the biggest internal challenge to her leadership since her tenure as German leader began in 2005. Any mention of Ralph Brinkhaus, the man who usurped her ally Volker Kauder as party whip in a recent vote, drew a cheer from the young delegates, who guard a reputation for preserving the party's traditional values.

The mood, many remarked, had changed since last year. The discontent was especially apparent among the delegations from Hesse and Bavaria, who are fighting desperate election campaigns in their home states, and who were not slow to blame the federal government's recent infighting for their dire poll numbers. Indeed, the Bavarian delegates of the Christian Social Union (CSU) stayed demonstratively in their seats as Merkel entered the arena on Saturday morning, while the rest of the room stood up to applaud.

Read more: What now for Angela Merkel?

No more nationalism

Nevertheless, the chancellor delivered a largely well-received speech, typically detail-rich and atypically passionate, for an audience mostly determined to show that they still believed in her.

She underlined Germany's economic prosperity before expounding on the challenges ahead – specifically upgrading digital infrastructure and keeping up with China when it comes to making batteries, before lamenting all the time lost by spending the last three years arguing about migration.

She was also defiant about the rise of far-right nationalism across Europe. "What did the founding fathers of Europe mean when they said nationalism will lead to war again?" she said.

"So my plea to you is: let's not start dividing ourselves into groups again. The migrants and the Germans. Those in the East and those in the West. The first thing is the stereotypes, secondly it's the thoughts being spoken out loud, the language, the hate-speech, and thirdly there are the acts against other groups."

But while she acknowledged mistakes had been made in the aftermath of the 2015 influx of refugees, the chancellor did not show nearly enough humility for some delegates, who, in the subsequent Q+A session, complained that she had given them a fine chancellor's speech – but not something to galvanize a flailing party.

Read more: After Chemnitz, poll shows east-west split on migration

Time running out?

The boldest questioner was Munich's Matthias Büttger, who got up to tell Merkel bluntly that he no longer believed the CDU could move forward with her in charge. "I think this leadership has run its course," he told DW afterwards. "It's about Merkel's politics and political style. This leadership has never been able to show strength. As ever it was a very detailed speech, which of course was right in certain things, but it showed no vision for our country, and no prospects for our future."

He also complained about the government's failure to find a good pension plan, but it was obvious what his real problem was: immigration. "The fact is that since September 2015 we still haven't properly accepted that wrong decisions were made, and the majority of the population, and the majority of the grassroots of the CDU and the CSU see it that way," he added. "And that is making everything the government does more difficult."

What comes next?

Meanwhile, journalists joked that the JU convention resembled an audition session for Merkel's successor. Indeed all of the post-Merkel CDU front-runners were scheduled to speak in the three-day event: Daniel Günther, state premier of Schleswig-Holstein, considered a liberal in the party; Health Minister Jens Spahn, the young insurgent not shy of right-wing populism; Armin Laschet, state premier of North Rhine-Westphalia, an elder statesman with an all-inclusive centrist approach; and CDU General Secretary Annegret Kramp-Karrenbauer, often considered Merkel's closest ally.

Of course these people batted away any notion that they were currying favor among the party youth. "State premiers are always up for discussion, but I always came to the Junge Union conventions, so this doesn't have anything to do with the chancellorship," Laschet told DW after his speech. "This is one of the few commissions where the CDU and CSU are together, and a lot of the Junge Union are the leaders of the future. That's why the chancellor is coming, several state premiers, and general secretaries – it's an obligation to be here, because it's a measure of the mood in the CDU."

But, in the face of devastating polling figures – the CDU/CSU is dipping below 30 percent in most national polls – it was impossible to avoid the question: is it time for Merkel to go? In fact, given that Germany's far-right populists have become so obsessed with Merkel and her fateful 2015 decision, wouldn't it be easier to fight the Alternative for Germany (AfD) without her?

JU leader Paul Ziemiak took a challenging tone in his opening speech on Friday: "If you want to be chancellor of this country, you have to be ready to lead this country into the future," he said. Indeed, with two state elections looming this month – in Bavaria and Hesse – no one wanted to rule out personnel changes in Berlin, at least behind closed doors. But still, the official line at the convention was clear: criticism is fine, but no demands for Merkel's head – at least for now.

"Of course there were voices in the Junge Union of dissatisfaction with the grand coalition in the last few weeks," said Philipp Heissner, a member of the JU leadership committee. "That's no secret … but I think the support for the chancellor is still very strong in the Junge Union and it will stay that way. I think the JU will be the last to support wing fights."