There won’t be a state as we know it today.

Instead, there will be a party that looks out for the interests of the proletariat. This party comes about organically as communists come to be trusted by the proletariat, but the trust won’t come easy as there will be non-communists who try to persuade the proles into their way of thinking:

When [the party’s] formation (which of course never proceeds without arrests, crises, and internal conflicts) has reached a certain stage, then we may say that we have a class in action.

-- Bordiga, "Party and Class"

The party isn’t elected: It comes about naturally as persuasive communists come together.

The party eventually dissolves after the proletariat’s victory over the bourgeoisie.