The leading candidate, Friedrich Merz, a conservative who has adopted many of the AfD’s hard-line positions on immigration, used his closing statement of the debate to promise his voters that he would never allow the AfD into his government. Under him, he said, the firewall would hold.

Founded in 2013, the AfD is controversial for its hardline on migration and asylum-seekers, with frequent rows surrounding its alleged invocation of Nazi symbolism.

Concern is growing over the far-right Alternative for Germany party’s rise ahead of the German election. Its U.S. supporters include Elon Musk and JD Vance.