Expletives create a sort of exception to our normal way of constructing sentences. Some grammar guides describe the expletive's grammatical function as that of a "false subject." That's why, they say, we make our verb agree with the word that follows it — the verb's "complement."
There is a monkey in the White House.
There are some clowns in the Capitol building.
Here is my official resignation.
Here are our plans for impeachment.
The "Oxford English Grammar" calls the expletives in such constructions the "grammatical subjects" as opposed the "notional subjects" — "a monkey," "some clowns," etc.