Barack Obama might have been the first United States presidential candidate to focus on social media and Twitter as part of his campaign marketing plan, but he's certainly not the last. It's not that Presidential Candidates like Twitter. They're doing it because Americans expect it. Presidential candidates have to go where the people are, so Twitter it is!According to research by Digitas, 82% of American adults use social media, and 88% of those social media users are registered voters. Seems like an important place to connect with those voters is the social web!Here are some interesting statistics from the study:

• 61% of respondents expect candidates in the 2012 U.S. presidential election to have a presence on the social web such as a Twitter profile.
• 38% of respondents overall claimed that the information they find on Twitter, Facebook, and other social media sites will help them decide who to vote for in the 2012 election just as much as TV and newspapers will.
• 51% of respondents between the ages of 19-34 stated that social networks will affect their voting choices just as much as traditional media.
• 38% of respondents between the ages of 35-44 said that social networks will affect their votes just as much as traditional media.
• 29% of respondents between the ages of 45-54 claimed that social networks will influence their voting decisions as much as traditional media.
• 23% of respondents over the age of 55 believe that social networks will impact their voting decisions as much as traditional media.

Click the image below (and then click it again when it opens in a new window) to view the full-size infographic with all of the details from the Digitas study.

As Colleen Taylor of Gigaom noted, this isn't the first time in history that the evolution of media has affected the way Americans make presidential voting choices. Taylor wrote, "John F. Kennedy's telegenic appearance during a crucial debate in 1960 famously helped boost him over rival Richard Nixon." After that event, televised presidential candidate debates became a significant source of influence.We're watching the same evolution occur right now as we head into the 2012 election season and Twitter, along with other social media tools, becomes a key component of candidates' campaign strategies.Image: AdAge