German Chancellor Angela Merkel is fighting for her political future on Sunday desperate to placate conservative rebels in her ruling coalition over immigration with a last-minute European deal, even as central EU states called the deal into doubt. If she is unsuccessful in convincing her political ally, CSU leader Horst Seehofer, that the deal will stick and limit immigration into Germany, she faces a political crisis that could end her parliamentary majority and, potentially, her career.

With CSU's two week ultimatum to reach an agreement on pushing back immigrants into Germany to their nations of origin set to expire tonight, Merkel's centre-right CDU party and its conservative Bavarian CSU allies are holding separate meetings to weigh the results of last week's EU summit, which agreed on collective measures by the bloc's 28 members to reduce immigration, AFP reports.

Merkel hopes the deals with European migrant discontents - mostly Italy which threatened to veto last week's summit until the last minute - and German neighbors will deter Interior Minister and CSU leader Seehofer from defying her by turning away at the border asylum seekers already registered in other EU nations. Such a unilateral move would force her to fire him, prompting a CSU walkout that would cost her her majority in parliament.

According to a document sent to coalition partners, Merkel sought to assuage the hardliners with deals with 16 other countries to return already-registered migrants if they reached Germany. The EU and bilateral deals were "only possible because the chancellor enjoys respect and authority throughout Europe," Germany's EU Commissioner and CDU politician Guenther Oettinger said in an interview with the Frankfurter Allgemeine Sonntagszeitung weekly. "That is very valuable for Germany, no-one should destroy it."

The German leader, who recently won a historic, third mandate, has warned that the issue of migration could decide the very future of the EU itself.

But a potential dealbreaker emerged when several central European nations including Poland, Hungary, the Czech Republic and Slovakia denied they had agreed to accept returned migrants.

Over the weekend, signs of reconciliation emerged after Merkel and CSU head Horst Seehofer met at the chancellery in Berlin late Saturday to discuss how to avoid a government crisis, according to Bild, and while Merkel’s CDU party published a position paper saying “we want to further reduce the number of refugees arriving in Germany”, it also caused new conflict with its statement that 14 EU countries had made a “political commitment” to take back refugees who originally arrived on their soil but moved on to Germany. As a result, Germany's ARD reported that the government leaders in the Czech Republic, Hungary and Poland denied having made any commitment at the summit.

This has prompted fears that a tentative deal could fall apart in the last minute: "Given the different statements from some EU member countries, one can doubt whether all of the decisions at the EU Council will become reality," head of the CSU parliamentary group Alexander Dobrindt told Bild am Sonntag newspaper.

As a reminder, in a marathon overnight session on Friday, EU leaders agreed to consider setting up "disembarkation platforms" outside the EU, most likely in North Africa, in a bid to discourage migrants and refugees boarding EU-bound smuggler boats. Member countries could also create processing centres to determine whether the new arrivals are returned home as economic migrants or admitted as refugees in willing states.

At the national level, Merkel also proposes that migrants arriving in Germany who first registered in another EU country should be placed in special "admissions centres" under restrictive conditions, according to a document she sent to the CSU and coalition partners the Social Democratic Party (SPD).

"There will be a residency obligation reinforced with sanctions," the document states.

On Friday, a happy Merkel told reporters that the hard won EU and bilateral deals were "more than equivalent in their effect" to Seehofer's demands.

And, indeed, the initial signs were positive, with the CSU's Bavarian state premier Markus Soeder saying on Saturday that "what has been achieved in Brussels is more than we originally thought.

But as German dpa news agency adds on Sunday, Seehofer himself was hardly as enthusiastic and said he was not happy with the results of EU summit which he said is not as effective as turning away unilaterally at Germany's borders people who have registered already in another EU country. Seehofer also rejected so-called "anchor centres" within Germany.

Meanwhile, the opposition from the 4 core Central European nations prompted Alexander Dobrindt, the CSU caucus leader in the national parliament in Berlin, to warn that it raises doubts about whether the EU deal on migration will be fully implemented.

The stakes of today's discussions are momentous not only for Merkel, but also for the CSU, which fears losing its absolute majority in Bavaria's state parliament. As AFP eloquently notes, "the "Free State" with its beer-and-lederhosen Alpine traditions, powerful industries and impenetrable dialect has a more conservative bent than other German regions."

The big danger for the CSU is that if it is seen as caving too far, it may lose even more support to Germany's the anti-refugee, anti-Islam phenomenon, the AfD, which succeeded in entering Federal parliament for the first time after the last German elections, at the expense of establishment parties. Opinion polls point to the AfD making a similarly spectacular entrance to Bavaria's parliament in October.

The big problem for Seehofer is that weeks of "Merkel-bashing" have failed to help the CSU, as a Forsa poll last week showed around 68% of Bavarians backed Merkel's quest for a Europe-wide answer to migration rather than Germany going it alone.

How the CSU resolves this dilemma will impact the fate of Merkel, and could have dramatic consequences for the future of Europe.