On Sunday the Christian Social Union (CSU) are set to meet to vote on whether to back Horst Seehofer in his plan to turn asylum seekers back at the German border. If Seehofer follows through, the move will have incalculable consequences for German politics.
What is the problem?
Germany's conservative parties are a little like two crime families who work together as long as one stays off the other's turf. This has worked out pretty well over several decades as the CSU have sat in power in Munich, while the CDU dominated politics on the federal level.
There were unwritten rules to their collaboration though. Whereas the mafia (at least in the films) drew a line at bringing drugs into the country, the unspoken code of German conservative politics was: no immigrants (or at least, not too many).
When Angela Merkel decided not to close the borders as thousands of refugees crossed the border in 2015 she broke this rule. Ever since then the ageing boss of the CSU, Horst Seehofer, has been seething. Throw into the mix a hot-headed upstart who is challenging Seehofer's grip on power in the CSU and you not only have the ingredients for a ropy Hollywood movie, but also for real-life German politics.
Now Interior Minister, Seehofer has loudly declared that Germany has been too soft in applying EU law on asylum seekers. He was set to publish an “asylum masterplan” a little over two weeks ago, which would have given him the power to stop migrants coming into the country.
But Merkel bluntly rejected the proposal.
Ever since then conservative politics in Germany has been in a state of meltdown. Seehofer claims he can't understand why Merkel rejects what he describes as a technicality, while Seehofer has been accused of putting Bavaria's interests above those of Germany and Europe.
And with state elections coming up in Bavaria in the autumn, there is every reason to believe that Seehofer and the young upstart Marcus Söder aren't thinking about much else other than what goes on inside their own territory.
The upshot of the controversy was that Seehofer gave Merkel two weeks to find a deal on migrants with other EU countries, otherwise he would shut the border whether she liked it or not.
If he goes ahead, decades of peace between the conservative clans will come to an end. Seehofer will force Merkel to fire him and their Bundestag alliance will be over. A pitched battle for power will commence in the build up to Bavaria's autumn elections. Things could get very messy.
Time is up
Seehofer's deadline is up this Monday. On Sunday, the most important members of the CSU will come together in Munich to discuss what steps they'll take next.
In the meantime, Merkel has been wringing every last inch of guile out of her...