Tracking every click in attempt to sway voters

A few weeks ago, Thomas Goddard, a community college student in Santa Clara, Calif., and a devoted supporter of U.S. President Barack Obama, clicked on mittromney.com to check out the candidate’s position on abortion.

Then, as he visited other websites, he started seeing advertisements asking him to donate to Mitt Romney’s campaign.

“It doesn’t make any sense,” Goddard said. “I’m the opposite of a Romney supporter. But ever since I went to the Romney site, they’ve been following me.”

One of the hallmarks of this campaign is the use of increasingly sophisticated — but not always accurate — data-mining techniques to customize ads for voters based on the digital trails they leave as they visit Internet sites.

It is a practice pioneered by online retailers who work with third-party information resellers to create detailed portraits of consumers, all the better to show them relevant marketing pitches.

Now, in the election’s final weeks, both presidential campaigns have drastically increased their use of such third-party surveillance engines, according to Evidon, a company that helps businesses and consumers monitor and control third-party tracking software.

Over the month of September, Evidon identified 76 track- ing programs on barackobama. com — two more trackers than it found on Best Buy’s website — compared with 53 in May. It found 40 trackers on mittromney.com last month, compared with 25 in May.

The campaigns directly hire some companies, like ad agencies or data management firms, that marry information collected about voters on a campaign site with data about them from other sources. But these entities, in turn, may bring their own software partners to the sites to perform data-mining activities like retargeting voters or tracking the political links they share with their social networks.

Now some consumer advocates say the proliferation of these trackers raises the risk that information about millions of people’s political beliefs could spread to dozens of business-to-business companies whose names many voters have never even heard. There is growing concern that the campaigns or thirdparty trackers may later use that voter data for purposes the public never imagined, like excluding someone from a job offer based on his or her past political affiliations.

“Is the data going to be sold to marketers or shared with other campaigns?” said Christopher Calabrese, the legislative counsel for privacy-related issues at the American Civil Liberties Union. “We simply don’t know how this information is going to be used in the future and where it is going to end up.”