Bulgarian SSR?

[PigmerikanMao]

I've been noticing in a couple of cold war documentaries I've watched recently that there have been passing references to Bulgaria's attempt to join the USSR as a SSR. Does anybody know if there is any weight to this claim? If Bulgaria tried to join the USSR, why were they not allowed to?

Not sure if this belongs in OI or OI Learning. Mods feel free to move it.

[l'Enfermé]

Of all the People's Republics, Bulgaria under Zhivkov was the most loyal to the USSR, especially during the Brezhnev era. There were many attempts by the Bulgarians to join the union, in the 60s and 70s especially(even though after the 1960s promoting Bulgarian nationalism was Zhivkov's official policy). The plans fell through because, I think, of Soviet resistance. The other People's Republics might have become worried that the USSR would try to swallow them also, the Yugoslavians would get pissy too, and NATO, and besides, Bulgaria didn't even border the USSR, the Romanians were in the way.

[PigmerikanMao]

There were similar movements in Bavaria and Sicily to join the United States after WWII, I presume they were blocked for the same reasons then. I was wondering if it had to deal at all with economics and Bulgaria's economic dependency, but maybe it could have just been political. Are there specific reasons Bulgaria was so close to the USSR as opposed to the other People's Republics?