Beatrix von Storch faced an immediate challenge from political talk show host Anne Will, who confronted her with one of her own Facebook posts blasting Merkel for "ruining our country like no one since 1945".
"I'm taking bets that Merkel will leave the country when she steps down – for security reasons," the post continued.
When Will asked if she was serious about this, von Storch said "I mean that she should go into exile to Chile or South America".
It was a pointed reference to the fact that many Nazi war criminals, such as Holocaust mastermind Adolf Eichmann, fled to South America following the defeat of the Hitler regime in 1945 and escaped prosecution for decades.
Chile was also the final destination for East German Socialist Unity Party (SED) leader Erich Honecker following the reunification of Germany in 1990.
But the South America link is especially resonant at a time when many far-right Merkel opponents are explicitly comparing the Chancellor and her government to Nazi war criminals.
The furthest-gone conspiracy theorists say leaders plan to "replace" the German population with Muslim immigrants - just as the Nazis wanted to replace eastern Europeans with German settlers.
There were audible gasps from the audience at Storch's remarks, and protests from fellow guest Armin Laschet, deputy leader of Merkel's Christian Democratic Union (CDU)
But von Storch – who is also an MEP – refused to back down, although her speculations about Merkel's future were hardly the "return to the facts" she had promised.
Fighting the causes of flight
Von Storch's wild imagination was a hard act to follow for the mainstream politicians discussing whether Germany should ape Austria's example by introducing an upper limit on the number of migrants allowed into the country.
"You and your upper limit. We've already heard what you've got to say at the lower limit!", Laschet retorted to von Storch.
Laschet tried to defend Merkel's policy, saying that she had never said that everyone arriving in Germany would be allowed to stay – and emphasizing the importance of resolving the conflicts driving refugees towards Europe.
For instance, the Rhineland politician also praised the fact that Russian President Vladimir Putin "is co-operating" in Syria – despite allegations that Russian forces' bombs have killed more than 1,000 civilians.
'If we don't manage this, Europe will break apart'
Meanwhile, a representative from the Evangelical Church was duking it out with a politician from the Christian Social Union (CSU), Merkel's conservative Bavarian allies.
Former Interior Minister and senior serving MP Hans-Peter Friedrich repeated the CSU's call for an upper limit on refugee arrivals and tighter security at the European Union's external borders.
But Evangelical Church council chairman Heinrich Bedford-Strohm demanded to know "what happens to the people who are kept out of the EU? I'd really like to have an answer!"
"It's not Christian to arouse hope in people that we can't fulfil," Friedrich said.
With little to agree on when it came to refugees, all the participants seemed able to do was lament the impact of border measures on Europe.
"I see the European internal market endangered" if heavy goods trucks have to wait for hours at EU borders rather than passing straight through, Merkel deputy Laschet said – adding that this, too, was weighing heavily on the Chancellor's mind.
"Europe is a great project for peace," Church representative Heinrich Bedford-Strohm said. "If we don't manage this, then Europe will break apart."