We have voter rolls (preprocessed) into elastic search. We do search using data available from twitter (name & location, mostly). We can't match all twitter users who are voters, but we have a very low false-positive rate.

And getting lower tomorrow. And then going up in efficacy, while maintaining confidence. There's a ton more we can do with this. :-)

Twitter's actually the hardest nut to crack—pretty sparse user info available. Facebook and LinkedIn have a much higher hit rate, but they don't have such easy streams to grab.