next Image 1 of 2

prev Image 2 of 2

German conservatives are warning the center-left Social Democrats that they're not prepared to renegotiate preliminary agreements on issues such as migration after their prospective partners narrowly backed coalition talks.

Chancellor Angela Merkel's conservative Union bloc and the Social Democrats are expected to open formal negotiations this week on extending their coalition of the past four years.

On Sunday, a Social Democrat congress endorsed that plan, helped by pledges to seek more palatable compromises on issues such as health policy and the right of migrants' families to join them in Germany than were reached earlier this month.

Julia Kloeckner, a deputy leader of Merkel's Christian Democrats, told ARD television Monday that the upcoming negotiations will deepen details of what was already agreed "but not bring up something that was already rejected."