Question: Say a group of people vote for a leader in an election but the leader then goes on to "*speak for the people*" but actually he's speaking for himself and his cronies. I'd like it to be clearly in a derogatory sense.

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> "Mr ..... claimed he was speaking on behalf of the people who voted for him but he was actually **[stealing]** their voice"
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What word would best fit here?

Answer: 
The answer is in the title of your question

[Misrepresent](http://www.merriam-webster.com/dictionary/misrepresent)

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> to give a false or misleading representation of usually with an intent to deceive or be unfair
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> to serve badly or improperly as a representative of
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For example:

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> He claimed he was speaking on behalf of the people who voted for him, but he was mispresenting them when he announced the new policy that would...
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[Ventriloquize](http://www.dictionary.com/browse/ventriloquize):

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> to speak or sound in the manner of a ventriloquist.
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