The success of the Alternative for Germany, or AfD, is a sign of the times. Across Europe, far-right parties once on the fringe have gone mainstream.

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.

Germany's conservatives won the national election on Sunday, while the far-right Alternative for Germany came in second, its best ever result.