I have always understood this to have been Bordiga's position, since he came to the conclusion that the 'proletarian state' in Russia should have been directed not by the Russian party but by the International acting as a world party. Also that he argued this position at the 6th Enlarged Executive of the CI in 1926. But I am not certain of the precise reference and I may be mixing up different things.
In any case, the later organisational development of the Bordigist current reflects the idea that there should be a single international communist party (even if they made the mistake of considering that they were already 'it')




http://www.revleft.com/vb/why-not-international-t59122/index.html
I'd like to know where one Bordiga specifically wrote about the need for one international party, as opposed to the "International" model.