> Google and Facebook told ProPublica they do not offer this kind of political matching service.
Google's privacy policy classifies political beliefs as "sensitive personal information," which should not be used for online ad targeting. Facebook does allow political campaigns to target political advertisements, but only on the basis of political beliefs reported by the users themselves, rather than information culled from their voting records.
And they use every scrap of information they can collect about me to send the right ads to my screen. If you put personal data on the Internet, you shouldn't be surprised how it's used. The only thing information I really expect to stay private is my credit card numbers, otherwise, I just don't give out much information.