About 40 rebels from German chancellor Angela Merkel’s conservative party have sent her a letter demanding an about-face on her liberal refugee policy.

Citing slipping poll numbers and mounting scepticism among Germans about the country’s ability to handle the influx, which brought nearly 1.1 million newcomers last year, the Christian Democratic Union (CDU) MPs said Merkel must face up to reality.

“In light of the developments in recent months, we can no longer speak of a great challenge – we are on the verge of our country being overwhelmed,” they wrote, in the letter addressed “Dear Madam Chancellor” and obtained by AFP.

The appeal marked the largest single expression of dissent by members of Merkel’s own camp since the refugee crisis hit Germany in September. The CDU has 256 seats in the Bundestag lower house of parliament.

“We do not want to divide the CDU parliamentary group – we are only asking for the law to be applied,” one of the initiators of the letter, Christian von Stetten, told AFP.

The signatories said that quick processing of asylum applications, housing in “appropriate” conditions and “successful” integration of newcomers were all impossible if “the number of arrivals remains this high or begins to climb again in the spring”.

They urged Germany to resume applying the EU’s Dublin asylum regulations, which say that refugees must seek asylum in the first member country that they land in.

Merkel, who has attempted to rally Germans with the slogan “We can do it”, has pledged a “tangible reduction” in the number of asylum seekers arriving in Germany in the coming months.

This would entail a raft of new measures at the national level and in cooperation with EU partners and neighbours of war-ravaged Syria, from which around 40% of last year’s new arrivals came.

But she has steadfastly rebuffed calls to close the German border, saying it would be unconstitutional and ultimately ineffective.

Time is running out to turn the tide ahead of three key state elections coming up in March, when the right-wing populist Alternative for Germany party hopes to gain seats at the CDU’s expense.

The public mood has soured in particular since a rash of sexual assaults and robberies during New Year’s Eve celebrations in the western city of Cologne blamed on North African and Arab migrants.