The Original Poster's sentence is badly punctuated, but entirely grammatical.
Indeed this government - neither their great wealth nor their many supporters will benefit them on election day; they will fail.
This sentence looks very much as though it has this government for a subject. Beware! This is, in fact, not the case. Let's simplify the sentence, investigate it and put it all back together again.
The string of words running neither their great .... election day is parenthetical. This means that it is not integrated into the grammar of the main clause. It is like an aside by the author. The fact that it is parenthetical is shown by the fact that we could literally put it in brackets or dashes:
- Indeed, this government (neither their great wealth nor their many supporters will benefit them on election day), they will fail.
Or we could even leave this whole section out altogether:
- Indeed, this government, they will fail.
Now, the sentence above is a bit easier to get to grips with. Notice that that word indeed is an adjunct. It links back to something that was said in a previous sentence and emphasises that what is coming up next is emphatically true. Being an adjunct this word is not integrated into the main clause either. This leaves us with:
- This government, they will fail.
Now, this sentence has the same kind of structure as:
As mentioned above, it's tempting to think that This government or Bob are the subjects of these sentences -but they aren't. Notice that these phrases can come at the end of the sentence as easily as the beginning:
- They will fail, this government
- He's a great guy, Bob.
We can also turn these sentences into yes/no questions. The phrases that invert with the auxiliary verbs will be the subjects:
- This government, will they fail?
- Bob, is he a great guy?
Notice as well that both sentences are well-formed without the phrases this government or Bob. This shows, firstly, that they and not this government is the subject of the Original Poster's question. Secondly, it also shows that this government is also an Adjunct in the sentence. It doesn't form part of its essential structure.
The sentence therefore has a subject they, whose predicate is ostensibly will fail. It has three parenthetical elements which are not integrated into the clause structure:
- the government
- neither their great wealth nor their many supporters will benefit them on election day
This last element has the structure of a complete sentence which has been interpolated into the main one. It, too, is well formed. It has a co-ordinated subject neither their great wealth nor their many supporters and a predicate will benefit them on election day.
Note: Notice that it would be easy to confuse this sentence with one such as:
- This government is neither their great wealth nor their many supporters ...
In the sentence above, which seeks to differentiate the government from their supporters or their financial reserves, the phrase the government would be the subject and the string beginning is neither would be the predicate.