Prospective chancellor takes startlingly aggressive line against those protesting against gamble with AfD. The German conservative opposition leader, Friedrich Merz, whose party is widely tipped to win this month’s general election, defended his hardline migration proposals after a wave of protests accused him of breaching the time-honoured “firewall” between the far right and centrists. In an uncompromising speech to a party congress of his Christian Democratic Union (CDU) in Berlin, Merz said he was confident they would win the 23 February vote “with a very good result”, well ahead of the anti-immigration, anti-Islam Alternative für Deutschland (AfD), which has been consistently placing second in the polls.

Five days after passing a non-binding resolution on border policy with the votes of the far right – marking a historic breach of a taboo – Merz renewed a promise to bar any formal cooperation with the AfD in future. “We will not work with the Alternative für Deutschland – not before [the election], not after – never,” he said to a lengthy standing ovation from delegates. The AfD “stands against everything that our country and our party built in the last years and decades”, he said. “It is our most important opponent in this election campaign. We want to make it small, we want to make it a footnote.”.

Referring to the tens of thousands of demonstrators who turned out in cities across Germany at the weekend to criticise Merz’s high-stakes gamble with the AfD, the CDU leader took a startlingly aggressive approach, accusing the protesters of hypocrisy. Merz demanded: “I want to know: where is the uprising of decent people?” in the face of a “never-before-seen hatred of Israel” since the 7 October attacks by Hamas and “an antisemitism that deeply shames us all … against which the reaction has been too hesitant”.

“I say to all those who were out yesterday: you picked the wrong date and the wrong issue,” he said. Drumming home a law-and-order message in the last weeks of the campaign, Merz argued that mainstream parties had to offer a tougher response to violent crimes, such as last month’s deadly stabbing attack against small children in the southern city of Aschaffenburg, or risk losing ground to extremists.

“The open outbreaks of violence on our streets and in well-known parts of town around certain events such as New Year’s Eve and May Day undermine the faith of our population in the rule of law and allow our state to often appear powerless and defenceless,” he said. Merz said a government under his leadership would show that “this time-tested democratic order in our country is still able in a reasonable period of time to face up to challenges”.

Sign up to This is Europe. The most pressing stories and debates for Europeans – from identity to economics to the environment. after newsletter promotion. “If we don’t manage that in the coming years, then Germany risks sliding into leftist or rightwing populism,” he said. Leading in the polls for several months, Merz has faced intense criticism over the last week from the centre-left parties, dissenters in his own camp and pundits across the political spectrum for his risky gambit with the post-Nazi consensus to isolate the far right.

The failed non-binding resolution put forward by Merz with the knowledge it would probably only pass with AfD support called for tougher measures to fight irregular immigration, including turning larger numbers of people back at the border. Critics have said many of the proposals violate EU or German law. On Friday, the German parliament rejected CDU-sponsored draft legislation calling for a tightening of immigration controls that risked being the first bill to pass with votes from a far-right party.