One site I know that does it right is
https://www.betfair.com/sport/politics it works mostly for country like the UK and USA.
However, you need to ask yourself if you really want to do it. I feel politics betting is easily manipulated though.
We agree that Betfair does a pretty good job. Also PredictIt.
Here at
exbet.io we also hope to be offering a broad selection of Politics markets when we launch.
But we are intrigued... when you say that "politics betting is easily manipulated"... can you give some examples?