Obviously for a good story, Harry can't just steamroll everyone in his way -- I'd make it such that Harry by himself is a substantial power bloc but not as seen here able to simply impose his will. Conflict would come from politicking to get the maybe 20 or 30 votes he needs to get an unassailable majority on every issue, and power plays by purebloods looking to get votes back from his collection, and attempts to exploit his ignorance of Wizarding politics and etiquette to discredit or eject him and so on... and toss in "power/responsibility" themes where he discovers things he has no interest in that he must take a stand on, and trying to figure out who to trust outside his friends. Basically turn this into an "I am now powerful beyond all reckoning, and it has painted a proportionally-sized target on my back. And chest."
-- Bob
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Then the horns kicked in...
...and my shoes began to squeak.
-- Bob
---------
Then the horns kicked in...
...and my shoes began to squeak.