In opposition since losing the 2015 election, the centre-left Social Democrats have followed a line on immigration that has often resembled that of the strictly anti-immigration DF.
This, along with similar policies in other areas like social welfare, has led to the two parties finding common ground against prime minister Lars Løkke Rasmussen's coalition government, most recently last month, when the PM was forced into a climbdown over increasing the retirement age.
DF party leader Kristian Thulesen Dahl called Wednesday for the Social Democrats, who hold the largest number of seats in parliament, to confirm that their policy on immigration would not change should they enter government with left-of-centre allies after the next election.
“I am asking the Social Democrats to take the clear next step that will not only clarify the party's immigration policy, but also confirm that the other parties must accept that it will not change after election,” Dahl told the Jyllands-Posten newspaper.
The DF leader added that continued cooperation between the two parties was dependent upon the Social Democrats retaining their current hard line on immigration.
Social Democrat political spokesperson Nicolai Wammen told Jyllands-Posten that the party would look to work with DF on immigration should it be elected.
“There is a large majority in parliament behind the current immigration policy. A Social Democrat-led government would practice immigration policies across the floor. In other words, including DF,” Wammen said.
“We will not implement immigration policies dictated by [left and centre-left parties] the Social Liberals, Red-Green Alliance or Alternative,” Wammen continued.
But Wammen declined to use the word “guarantee”, according to Jyllands-Posten.
DF's insecurity over Social Democrat policy is itself a consequence of previous demands by the Social Liberals (Radikale Venstre) for concessions on immigration.
The centre-left Social Liberals succeeded, for example, in getting the Social Democrats to repeal a point system for family reunification during negotiations to form the coalition government in 2011.
“If we are to provide parliamentary fundament or vote for a Social Democrat-led government, then of course we expect to have influence, including on immigration,” Social Liberal group chairperson Sofie Carsten Nielsen told Jyllands-Posten.
“We will not support a political project that is defined by a common ground between [Social Democrat leader] Mette Frederiksen and the Danish People's Party,” Nielsen added.