By Emily Steel in New York and Robert Cookson in London

Financial Times Subscribers, click here.

Barack Obama and Mitt Romney’s presidential campaigns are ramping up use of internet technologies to track voters despite evidence that most Americans are uncomfortable with the practice.

With three weeks until the election, new data reveal that both campaigns have deployed an unprecedented number of online tracking tools on their websites. These tools can be used to create profiles about people’s internet habits and target them with personalised ads when they visit other websites.

High quality global journalism requires investment. Please share this article with others using the link below, do not cut & paste the article. See our Ts&Cs and Copyright Policy for more detail. Email ftsales.support@ft.com to buy additional rights. http://www.ft.com/cms/s/0/de9ebb3e-1a08-11e2-a179-00144feabdc0.html#ixzz2A1qq25XY

BarackObama.com hosted 160 unique tracking technologies on its site from May until August, according to Ghostery, a firm that monitors online tracking. MittRomney.com had 110 unique tracking technologies over the same period.

“The presidential campaigns are digging much deeper – or at least casting a wider net – than a typical site,” said Andy Kahl at Ghostery. “With such aggressive ad campaigns that span such a relatively short amount of time, both camps endeavour to leave no stone unturned.”

US presidential campaigns have historically served as testbeds for new advertising techniques and often influence corporate marketing strategies across the globe.

The Democratic and Republican campaigns use third-party data-tracking companies that also work for commercial clients which could potentially reuse the information. Data about voters’ visits to political sites could be incorporated into tracking companies’ consumer dossiers.

“Ad networks aren’t only interested in political affiliation during the presidential campaign,” Mr Kahl said. “Online data collectors are positioning themselves for landslide wins.”

High quality global journalism requires investment. Please share this article with others using the link below, do not cut & paste the article. See our Ts&Cs and Copyright Policy for more detail. Email ftsales.support@ft.com to buy additional rights. http://www.ft.com/cms/s/0/de9ebb3e-1a08-11e2-a179-00144feabdc0.html#ixzz2A1qtSP6J

Neither campaign flags the tracking on its homepage, but both disclose the practice in their privacy policies.

The Obama campaign said on Friday that it stipulates that third-party partners not use data collected on its site for other purposes.

“We are committed to ensuring that all of our voter outreach is governed by the highest ethical standards,” said the Romney campaign, adding it ““respects the privacy rights of all Americans”.

Just over half of adults likely to vote in November were unaware that political campaigns were using such tracking technologies, according to a poll conducted in September by research firm Toluna. Sixty per cent of those polled said they were uncomfortable with the practice.

High quality global journalism requires investment. Please share this article with others using the link below, do not cut & paste the article. See our Ts&Cs and Copyright Policy for more detail. Email ftsales.support@ft.com to buy additional rights. http://www.ft.com/cms/s/0/de9ebb3e-1a08-11e2-a179-00144feabdc0.html#ixzz2A1qvYxwb

The Obama and Romney campaigns are also sending targeted emails, but the Obama campaign appears to be tapping more sophisticated personalisation technologies, according to an analysis by email marketer StrongMail. On Thursday, Amanda Orr, a voter based in Washington, received an email from the Obama campaign embedded with names of three Facebook friends who live in North Carolina, urging her to encourage them to vote.

High quality global journalism requires investment. Please share this article with others using the link below, do not cut & paste the article. See our Ts&Cs and Copyright Policy for more detail. Email ftsales.support@ft.com to buy additional rights. http://www.ft.com/cms/s/0/de9ebb3e-1a08-11e2-a179-00144feabdc0.html#ixzz2A1qy8Teb

“We have to, as a society, have a debate about the boundaries we want to place around political communication and data mining,” said Joseph Turow, a professor at the Annenberg School for Communication at the University of Pennsylvania.

Political data mining has reached a high as US lawmakers and foreign regulators have become increasingly concerned about digital privacy. In February, the Obama administration unveiled a “Consumer Privacy Bill of Rights” to provide more protections for consumers and pledged to work with Congress to develop more robust privacy legislation.

“American consumers can’t wait any longer for clear rules of the road that ensure their personal information is safe online,” Mr Obama said in a statement at the time. “As the Internet evolves, consumer trust is essential for the continued growth of the digital economy. That’s why an online privacy Bill of Rights is so important.”