How do you form the European Union?
Viewing post in Social Democracy: An Alternate History comments
You have to successfully negotiate the remaining Versailles obligations for starters.
Then you need to have good enough relations with both the east and west. after that, you can take the decision and eventually form the EU.
It can help in the Austrian parliament crisis if you manage to form it quick enough.
You need the foreign ministry for this, obviously.
I mean, in 1925, Edvard Beneš was in favor of the 'United States of Europe', so there was already some (very) slight leverage for the concept of the EU.
Edit: What I said isn't trying to change the fact that the EU was probably more unrealistic than other alternative historical events, but I'm saying that it was possible.
Make sure you do everything to get close to Europe; you can expose rearmament plans, drop the case for the Weltbuehne trial, get closer to both West and East until you can negotiate three times for creating a European Union. I assume getting closer to the British and French centre-left parties helps too!
The reverse is also true -- do not annoy Europeans by growing the military, forming a customs union with Austria etc.