The far-right Alternative für Deutschland (AfD) party is planning to transform Germany into an authoritarian state similar to Russia, the country’s vice-chancellor and economics minister, has warned, tacitly backing calls to ban the party. Speaking a week after it emerged that party members had participated in a meeting to discuss mass deportations, allegedly including German citizens, Robert Habeck said the danger the party posed to democracy had been gravely underestimated. As a fifth night of anti-AfD protests saw tens of thousands of people take to the streets of German cities, with more expected later on Wednesday, Habeck appeared to support calls to outlaw the party, while stressing the risks of such a move “dangerously backfiring” were it to fail. “The damage that a failed attempt would cause would be massive. Which is why if a case is put, it would have to absolutely 100% stand up in court. It’s something you have to consider very carefully,” the Green politician told the magazine Stern. Such a decision would lie with Germany’s constitutional court “and the hurdles are, as they should be, very high”, he said. It would be far better for the AfD to be beaten democratically at the polls, he added. “The rightwing authoritarians are concerned about an attack on the essence of the republic,” Habeck said. “They want to turn Germany into a state like Russia and are systematically preparing for this.” The AfD has shifted to the right since its founding in 2013 and has seen a steady increase in its popularity in recent months, in some cases outpolling the government parties. Over the past week, media and political observers have scrutinised the evidence as to who was among the AfD members, neo-Nazis and rightwing extremist Identitarian movement attenders at the November gathering in Potsdam. On Wednesday, the Werte Union, a self-described arch conservative grassroots movement within the Christian Democratic Union (CDU) and its sister party, the CSU, admitted that two of its members had been in attendance. But the Werte Union, which seeks to restrict immigration, bolster the German military and reduce taxes, accused the investigative bureau Correctiv, which revealed that the meeting had taken place, of exaggerating the nature of the agenda. At the same time it admitted that the topic of “remigration” had been discussed. It said its members had been invited as private guests and not as representatives of the Werte Union. The Werte Union’s chair, Hans-Georg Maaßen of the CDU, recently announced his plans to transform the movement into a party in its own right. The CDU is attempting to expel him. On Wednesday, Correktiv is due to present its research at the Berliner Ensemble theatre, and has said it will bring further details to light. The chancellor, Olaf Scholz, tweeted on Wednesday: “I am grateful that tens of thousands of people have been going on to the streets of Germany in recent days to protest against racism, rabble-rousing, and for our liberal democracy. That gives us courage and shows: there are far more of us democrats than those who seek to divide.” Lars Klingbeil, the chair of the ruling Social Democrats, called on “all the sensible people” who had so far not spoken out against the AfD, “to turn up the volume”. Katharina Dröge, the parliamentary leader of the Greens, told the news network RND: “We’re all called on now, in our private lives, in the workplace, at sport, when shopping, to clearly state that voting for the AfD is to vote for rightwing extremists, who pose a threat to democracy.” A fledgling alliance of anti far-right groups calling itself Hand in Hand, which so far includes more than 120 organisations, is planning nationwide demonstrations against the AfD, including a human chain around the Reichstag parliament building in Berlin, under the slogan “We are the firewall”. Tareq Alaows, one of the organisers who has been building the alliance since the summer in reaction to the AfD’s rising poll ratings, told the newspaper Süddeutsche Zeitung: “If the political parties can’t succeed in stopping the rightwing extremists, we have to create a human firewall against them.”