The study aimed to examine how the five presidential candidates - Barack Obama, Mitt Romney, Rick Santorum, Newt Gingrich, and Ron Paul - used Twitter in their 2012 presidential election campaigns and how Twitter received information from the candidates and shared information with other Twitter users. Among 30 million Twitter who followed these five candidates, most individuals followed either Obama or one or multiple Republican candidates, but rarely followed across the party line. To find which model explains Twitter users following patterns better, the author examined the two-step flow model and the network model. Based on analysis of randomly selected 180 Twitter who followed any of the five candidates, this study found that their Twitter activities fitted the network model, in which shared information with each other beyond directly getting tweets from their favored candidate. In this network model, some of the seemed to emerge as opinion leaders by issuing plenty of tweets and having more followers than those they follow, also known as one-way friends. The author also downloaded the Twitter profile pages of the five candidates and all their tweets from when they set up their Twitter account through March 2012. To content analyze the tweets of the candidates, the author randomly selected 500 tweets from the five candidates, 100 from each candidate, and analyzed them to find emerging 11 categories, which covered mentioning of their performance and ideas, criticism of their opponents, solicitation, thanks to voters, personal-side stories, and event reminders. The five candidates heavily used Twitter as a hook to hashtags and http links that would provide more detailed information for followers. They still used Twitter mostly as a textual communication tool, but they slowly made a move to visuals. In terms of message content, Republican candidates heavily cited others, for example, the mass media, to describe their ideas and performance and to criticize their opponents. But Obama didnt seem to rely on external sources for the same purposes. This study used all 30 million Twitter to find which candidate they followed. But it used a small size of Twitter and tweets for other analyses. Future studies are suggested to analyze larger samples for more accurate results.