Sentence Correction

Hello,
Can you please help me with the below question,

However much United States voters may agree that there is waste in government and that the government as a whole spends beyond its means, it is difficult to find broad support for a movement toward a minimal state

The sentence as given is correct (option A).
Can you tell me why it is used as 'much United States voters' not as 'many United States voters'

much is not referring to voters. But it is referring to extent of agreement.
I.e. whether they agree fully or partially ... which is uncountable ...