Chancellor Angela Merkel's Christian Democrats (CDU) said Monday that it would become official party policy never to entertain the idea of entering into a governing coalition, or even engage in political cooperation, with the far-right Alternative for Germany (AfD).

CDU General Secretary Paul Ziemak said "anyone in the CDU who is pleading for rapprochement or cooperation with the AfD should know that they are talking about a party that tolerates right-wing extremist thought, anti-Semitism and racism within its own ranks."

"The CDU refuses any coalition or similar form of cooperation with the AfD. Period."

There have been several rumors that the AfD and the CDU might work together in recent years, as a large part of the AfD's voter base are former CDU voters who disagree with Merkel's bringing the party toward the center.

The CDU's statement came one day after Friedrich Merz, Merkel's onetime rival for leadership of the CDU, told the Bild am Sonntag newspaper the CDU was hemorrhaging voters in the more conservative wing of the party, particularly among "police officers and the military."

'The social and the national' remark sparks outrage

Monday marked the second time in four days that Ziemak was prompted to make such a declaration. Last week, he wrote on Twitter that "One more time for everyone taking notes: the CDU strictly rejects any coalition or cooperation with the AfD!!!"

This was a response to an open letter in the Mitteldeutsche Zeitung from two CDU lawmakers in the eastern state of Saxony-Anhalt, where support for the AfD is stronger than in the west.

The two wrote that the CDU had to "reconcile the social with the national." These words prompted outrage for the similarity to the phrase National Socialism, or Nazism.

The letter was considered to be even more in bad taste coming so soon after the death of Walter Lübcke, a pro-refugee CDU politician who was the leader of the district of Kassel in central Germany.

Watch video 02:05 Share German politician killing Send Facebook google+ Whatsapp Tumblr linkedin stumble Digg reddit Newsvine Permalink https://p.dw.com/p/3Kesc Politician's killing an 'alarm bell' for Germany

Lübcke was killed on the terrace of his home on June 2, shot in the head at close range. The two suspects who have been arrested in the slaying are known to hold far-right and neo-Nazi views.

Annegret Kramp-Karrenbauer, who has taken over from Merkel as head of the CDU, said the atmosphere of "hate and incitement" created by the AfD is partly to blame for the killing.

The CDU is planning to penalize any elected officials from its party who attempt to work with the AfD in the future.

es/cmk (AFP, dpa)

DW sends a daily selection of hard news and quality journalism. Sign up here.