SEEON, Germany (Reuters) - German Chancellor Angela Merkel’s conservatives and their Bavarian allies on Thursday floated the idea of a flexible target for how many asylum seekers Germany should accept each year as a compromise to end a row between them over immigration.

German Chancellor Angela Merkel gives a statement in Berlin, Germany, December 23, 2016. REUTERS/Hannibal Hanschke

The proposed compromise reflects worries among both the Bavaria-based Christian Social Union (CSU) and Merkel’s Christian Democrats (CDU) that divisions over a refugee cap, which Merkel has rejected, would harm them at the ballot box.

“The proposal envisages a concept for the establishment of a ‘breathing’ benchmark for the possible admission of people in need of protection in Germany,” CSU lawmaker Stephan Mayer and his colleague Armin Schuster of Merkel’s Christian Democrats (CDU) wrote in a letter to the chancellor and CSU leader Horst Seehofer.

The CSU wants a yearly cap of no more than 200,000 refugees, and Seehofer has said it is not a given that his lawmakers will join a coalition led by Merkel after a general election in September.

The conservatives have been bleeding support to the far-right Alternative for Germany (AfD), and Seehofer has faced criticism that his tough stance on immigration was a reaction to the rise of the populist party.

Seehofer is also looking ahead to a regional election in Bavaria in 2018, worried about losing votes then to the AfD, which now has seats in 11 of Germany’s 16 federal states.

The proposal contains no exact numbers, but calls for Germany to set a new target each year based on the humanitarian situation in crisis zones worldwide and on Germany’s ability to absorb newcomers.

The state of the labor market, the size of federal funds for the integration of refugees and capacity at reception centers in Germany’s 16 states are mentioned as criteria for setting a limit on immigration.

“I believe it is in the interests of both the CDU and CSU sister parties that we enter the federal election campaign united,” Mayer told CSU members at an annual retreat.

Schuster told Reuters it was critical to resolve the issue. “We have a bone of contention that is overshadowing all unity between the CDU and the CSU. That is why we must clear it up.”

Seehofer also said on Wednesday that a “reconciliation summit” he is due to hold with Merkel in Munich in February was still planned but that the program was not set.

(This story adds Seehofer’s first name on first reference, paragraph 3)