CDU leader Friedrich Merz has ruled out any such alliance but caused uproar last month by bringing a motion to parliament that was passed with AfD votes, breaching a long-standing taboo.

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.

German voters cast their ballots in Sunday’s election, with opposition leader Friedrich Merz claiming victory. Exit polls also indicate that Alternative for Germany, or AfD, is heading for the strongest showing for a far-right party since World War II.