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.

On Sunday, the country’s residents will vote in a pivotal election in which Ms Weidel's party, Alternative for Germany (AfD), is tipped to come in second. A snap election was called at the end of last year by current Chancellor Olaf Scholz, of the Social Democratic Party (SPD), when his coalition Government fell apart.

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.

The Tesla and SpaceX owner backs leader of the most extreme party in the fray for election crucial for the future of Europe; US Vice-President JD Vance also met her secretly in Munich

Germany's elections are taking place on Sunday, and it is the party set to finish second that is attracting much of the attention. The far-right AfD could win as many as 145 of the Bundestag's 630 seats, according to polling. This comes just 12 years after the party was founded.