"If on average one in two [asylum] applications is decided negatively, then the federal states have a duty to deport one thousand rejected asylum seekers every day," Peter Tauber, general secretary of the Christian Democratic Union (CDU), told the Rheinische Post (RP) newspaper.
"Of course it remains right that we manage this great challenge [of refugees entering the country]," Tauber said.
But he insisted that while the numbers of people arriving in Germany each day have fallen from around 10,000 in November to around 3,000 now "seen over the course of a year, that's still too many".
Be grateful or you're not welcome
Tauber added that there must be zero tolerance for those who come to Germany and commit crimes or fail to integrate.
Peter Tauber is a key figure in Angela Merkel's Christian Democratic Union (CDU). Photo: DPA
It's a call that has become louder in the wake of the New Year's Eve chaos at the main train station in Cologne.
So far more than 560 criminal complaints have been submitted for sexual assault as police lost control of crowds people who were reported to be of North African or Arab appearance.
"Hundreds of thousands gratefully accept the help, are learning German, want to integrate. And whoever doesn't use that chance, for them the message is then 'You can't stay here!'," Tauber said.
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And there was a warning in Tauber's words for Angela Merkel, who remains leader of the CDU but who was accused of ignoring "subterranean" levels of confidence among ordinary voters by one of her MPs last week.
"The atmosphere is of course tense at party gatherings, there are many questions, and the clear expectation that we make progress," Tauber said.