NEW YORK (AP) -- Voters clicking on President Barack Obama's campaign website are likely to start seeing display ads promoting his re-election bid on their Facebook pages and other sites they visit.
People searching Google for information about Mitt Romney may notice a 15-second ad promoting the Republican presidential hopeful the next time they watch a video online.
The campaigns are spending heavily on television ads and other traditional tools to convey their messages.
But strategists say the most important breakthrough this year is the use of online marketing to raise money, share information and persuade supporters to vote.
The practice, known as micro-targeting, has been a staple of product marketing and faces the greatest test of its political impact in the 2012 presidential race.