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 mainstream parties lost support while the far-right AfD (Alternative for Germany) gained ground in a poll published ahead of Sunday's election, underscoring concerns about the AfD's potential influence in the next parliament.