When Angela Merkel told women’s magazine Brigitte on Monday evening that she had changed her mind on gay marriage - now believing that lawmakers for her Christian Democrats (CDU) should be able to vote with their conscience - she set a sequence of events in motion she probably didn’t predict.
By Tuesday afternoon it was almost certain that a parliamentary vote would take place at the end of the week, after the Social Democrats (SPD) essentially broke the terms of their coalition agreement with the CDU to put the bill onto the legislative timetable.
Merkel’s party rank-and-file are now furious with their leader. While some of them no doubt support same-sex marriage, they fear that voting for it less than three months before the election will unnecessarily antagonise their conservative voter base.
The SPD turned the screws on the CDU even tighter on Wednesday, when they pushed for a “named vote” on the bill, meaning that how an MP votes will not be anonymous.
CDU politicians are now stuck between a rock and a very hard place. If they vote against the bill they risk seeming outdated - polling suggests around 80 percent of Germans want same-sex marriage legislation. If they vote for it, they will be letting the SPD get away with breaking the terms of the coalition agreement, and they will potentially push more conservative voters into the hands of the hard-line Alternative for Germany (AfD).
Even without CDU votes, the bill should just pass through the Bundestag. SPD, Green Party and Die Linke politicians are expected to universally support it, and together they hold a slim majority in parliament.
That’s not the end of the story though. Some conservatives claim the legislation is unconstitutional.
“The interior and justice ministries have always been of the opinion that same-sex marriage can't happen without a change to the constitution,” Günter Krings (CDU) told the Rheinische Post on Wednesday.
“There is a lot of evidence to suggest that the proposed change to the law will contravene the constitutional definition of marriage.”
The Grundgesetz (German constitution) itself is not specific on what constitutes marriage. In Article 6 it declares that "matrimony and family are strongly protected by the rules of the state," without going further on what matrimony means.
But, according to the Süddeustche Zeitung, the Constitutional Court - the highest legal authority in the land - insists that “the unity of a man and a woman still belongs to the essential components of marriage.”
If the Constitutional Court were to reject a new law on same sex marriage, the Bundestag would need to vote on a change to the constitution, something that requires a two-thirds majority.
How likely that is, we will only know after the national election on September 24th.