Goldstein and others say that while the use of consumer information by political campaigns received significant attention in the 2012 election, the public voter registration data, polling and the one-on-one contact with volunteers remain the bread and butter of most micro-targeting efforts.

Alex Kellner, who served as digital director for Terry McAuliffe's successful gubernatorial campaign last year in Virginia, used an aggressive online targeting campaign to place ads on Facebook, Pandora and other popular sites to get voters to the polls.

One ad targeted young Democrats. Some ads featured former President Bill Clinton. He said the effort led 90,000 people to click on the ad in the final days of the campaign to look up their polling place.

McAuliffe won the election by less than 60,000 votes.

"Am I saying that, alone, we won the race? No," Kellner said. "But we had impact."

Sun reporter Erin Cox contributed to this article.

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Targeting online ads

Political campaigns in Maryland are relying on an increasingly sophisticated online targeting techniques to connect with voters. Here's one example of how that effort might work:

A campaign uses voter registration data to identify Hispanic voters in a given county who are highly likely to turn out in an election.

The campaign turns the list of voters over to a site such as YouTube or Google, which matches as many names as it can on the list to individual IP addresses.

The campaign then buys advertisements that appear on individual computers before a YouTube video is shown or when a voter searches the Internet.