US President Barack Obama speaks during a "Twitter Town Hall" in 2011 in the East Room of the White House in Washington, DC. Social networks such as Facebook and Twitter are playing a growing role in ... more 

US President Barack Obama speaks during a "Twitter Town Hall" in 2011 in the East Room of the White House in Washington, DC. Social networks such as Facebook and Twitter are playing a growing role in US politics by helping users stay informed and energizing activists, a study showed Tuesday less