BERLIN (Reuters) - Germany may need to wait until next year for a new government as the three blocs trying to form an alliance are so far apart they will need a deeply detailed coalition deal, a senior Bavarian ally of Chancellor Angela Merkel has told Reuters. 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 migrants 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. Dobrindt said diverging opinions between the three parties meant they would have to nail down an in-depth deal.  We need, in a possible Jamaica coalition agreement, a significantly higher level of detail than was the case with the grand coalition,  he said.  The differences between the parties are big, so the agreements need to go deeper.  In their compromise struck on Sunday, the CDU and CSU agreed to limit to 200,000 the number of newcomers Germany would accept per year on humanitarian grounds. The FDP and Greens insist the conservatives  agreement cannot simply be copied into a coalition deal.  Senior Greens member Juergen Trittin accused the conservatives on Tuesday of violating Christian values because they wanted to keep suspending family reunifications for migrants granted subsidiary protection - those who do not qualify as refugees but need international protection. FDP deputy head Wolfgang Kubicki told Deutschlandfunk radio the conservative deal would not form the basis for cooperation and would not be implemented the way it had been agreed, saying:  That won t happen.  But Dobrindt, whose CSU is worried about losing its regional dominance in Bavaria s state election next year, said the allies  accord must be reflected in a coalition deal.  The regulations we have made in our joint paper -  Rules on Migration  - are of course an essential part of the negotiations and must also be found in a coalition agreement.  The intransigence of the CSU, Greens and FDP on the migrants issue points to difficult coalition talks that risk clouding the political outlook in Germany, which has been a source of stability in Europe during Merkel s tenure.  We want Europe to concentrate more on the big tasks and less on the small tasks,  Dobrindt said.  That means we must talk about bringing back responsibilities from Brussels to Germany - and the details of that will no doubt be difficult.   