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.

The leader of the Alternative for Germany (AfD) party has been endorsed by Donald Trump - and looks set to make huge gains in this weekend's snap election.

As Dr Weidel took the stage in Halle, the crowd started a chant that was a not-too-subtle play on a Nazi slogan, “Everything for Germany,” a phrase once carved on the knives of Nazi storm troopers. It is banned in Germany.