Angela Merkel's coalition has been shaken to the core by a dispute between her CDU party and its sister party the CSU.
Why is the meeting between Angela Merkel and Horst Seehofer so crucial?
The meeting on Monday evening between the German Chancellor and her Interior Minister is yet another last ditch attempt to defuse tensions between them over the ongoing issue of migration. Seehofer has said that the bilateral deals Angela Merkel negotiated in Brussels at a summit late last week to curb migration aren't good enough, he is instead pushing his own stringent "migration master plan". Tensions peaked on Sunday night when he announced his resignation - which he then withdrew, saying he will speak to her first for one final attempt to reconcile. But with Merkel unlikely to bend to his demands to unilaterally turn migrants away from Germany's borders, a resolution looks unlikely.
What happens next if he resigns?
Angela Merkel would have to accept his resignation, and then worry about who is going to replace him. During the negotiations to form a coalition government, the Bavarian CSU party got the keys to the interior ministry, meaning they have a say on who would replace him. But the CSU at the moment is split between MPs who back Seehofer and his migrant proposals and MPs who think that their party's growing anti-Merkel sentiment is causing irreparable damage to the 70-year alliance with their sister party. Seehofer supporters could decide to back out of the government altogether if he resigns, which would likely mean a collapse of the conservative block, and a collapse of the government.
Why are the CSU so obsessed with the issue of migration?
The number of refugees coming into Germany has fallen dramatically over the past two years so it seems strange that it is the issue now threatening to bring down the government. Seehofer and some CSU members can't quite forgive Merkel for the summer of 2015, when she allowed hundreds of thousands of migrants to come into Germany, mostly through Bavaria, without giving them a lot of warning. They blame her for the subsequent success of the far-right anti-migrant Alternative for Germany, which has been absorbing some Conservative support in the polls in Bavaria ahead of a crucial regional election there in mid-October. So this tough anti-migrant stance is also an attempt to stop the loss of votes to the far right.