Maybe onehash can be your website, but be carefully the odds changes because they change even if you already made the bet. Try to look this website hours before the elections came.
~
Unfortunately onehash isn't opening for me at all, so I can't check it myself, but I don't understand how is it possible that they change the odds even if you already made the bet. Shouldn't they accept your bet with initial odds, with odds which were when you made that bet? Because otherwise maybe you wouldn't bet at all.
I mean of course they can change the odds with time for the future players, but for those who already made the bet the odds should stay as they were when the bet was made.
On OneHash YOU are the one who is setting the odds. Odds are changing with every bet to bring emotions to the betting. For example if someone will now bet 100 BTC for Clinton, odds for Trump will rise as hell. The more bets is placed on the team / player or candidate the less are the odds for him.