I've been wondering whether the nominal associate of expletive there gets nominative, accusative or dative case in clauses with exceptional case-marking in other languages, since case isn't visible outside the pronoun paradigm in English.
I want there1 [TP t1 to be sandwichesNOM/ACC/DAT? at the party]
As the Wikipaedia article suggests, the objective case is typical for such nominals. In Latin and Greek, for example, the accusative case is used—although neither language normally has this expletive there expressed as a special word, the below is semantically identical to using English there is/are:
Dicit viros adesse [acc. mascl. plural]
"He says men to be present = He says that there are men (there/present)".
It is the same in Ancient Greek.
In English, the objective case is used in similar constructions (though without your sense of there):
He is there --> I want him to be there.
He is a teacher --> I want him to be a teacher.
It is clear that *I want he to be there is unacceptable. Both these examples and your example are historically the same construction in English.
It is the same in Dutch, with the sense of there you are looking for (er):
Hij was er --> Ik zag hem er zijn [note that the construction is a little bit contrived with this particular sense of the verb and the pronoun combined, but it's possible].
"He was there" --> "I saw him there be = I saw him be there".
to be. It's not going to letwantor any other verb assign case to its argument. I'm sure someone else can give you an answer that's not based on a hunch though.