Alexander Dobrindt, parliamentary floor leader of the Christian Social Union (CSU), said a coalition agreement would have to be more precise than the one that accompanied the right-left grand coalition in the last parliament.
After 12 years in power, Merkel was humbled in last month’s national election by a surge of the anti-immigrant far right and she must now broker a three-way coalition of her conservatives, the pro-business Free Democrats (FDP) and the Greens - a combination previously untested at the federal level.
The task is further complicated by the fact that Merkel’s conservative bloc compromises her Christian Democratic Union (CDU) and the right-leaning Bavarian CSU, whose alliance has been strained by her open-door refugee policy.
The conservative allies removed one obstacle to forming a new coalition on Sunday by agreeing a limit on the number of migrants arriving in Germany, sought by the CSU. But Dobrindt said in an interview with Reuters television that securing a three-way alliance would be difficult.
“As we know that the points that separate us outweigh those we have in common, one can have doubts about whether a coalition agreement is possible this year,” he said. “It is conceivable that we can’t complete in December and that final talks - if there even are any - will only possible next year.”
The three-way tie-up - dubbed a “Jamaica” coalition after the black, green and yellow colors of the three party blocs that match the Caribbean nation’s flag - is Merkel’s only realistic option of forming a government.
The center-left Social Democrats, her previous partners in an awkward “grand coalition”, insist they now want to go into opposition.
A Jamaica coalition was formed in the tiny western German state of Saarland in October 2009, but collapsed in January 2012. The same formation took power in the far northern region of Schleswig-Holstein after elections there in May this year.
At a national level, the CDU/CSU, FDP and Greens have deep differences on issues ranging from migration to European Union reform, tax and the environment.
But Merkel, asked in an interview with the RND group of newspapers whether such a coalition could nonetheless come to pass, said the parties had a mandate from voters that they needed to take on.
“It’s our joint responsibility, our duty in fact, to form a government from that and to pursue sensible policies for our citizens and country. I think that’s possible,” she said.