BERLIN — A key ally of Friedrich Merz has ignited a major political debate by suggesting the chancellor’s centrist conservatives should break a taboo and cooperate with the country’s most popular party: the far-right Alternative for Germany.

Michael Kretschmer, premier of the eastern state of Saxony and a member of the chancellor’s center-right Christian Democratic Union, is challenging Merz’s insistence on keeping the country’s firewall against the surging AfD ahead of crucial elections in September that could put the far-right party in charge of a region for the first time.

“Anyone who still talks about firewalls hasn’t recognized the signs of the times,” Kretschmer, who leads a minority government in Saxony, told the Handelsblatt newspaper in an interview earlier this week. “We need to talk to anyone who wants to talk.”