For Pew's most recent analysis, the fourth presidential cycle it has examined digital campaign efforts, the researchers expanded their examination to include Facebook, YouTube and Twitter, as well as official campaign sites and blogs.

Both candidates focused their online messages heavily on the economy, with Romney devoting a slightly greater percentage of his posts to that issue than Obama, hitting the president especially hard on jobs.

But posts on social issues such as immigration and healthcare appeared to resonate the most with social media users. For both candidates, their posts about such issues were retweeted or shared at several times the frequency as their economic messages.

All told, Obama's posts saw twice as many shares, views and comments as content from the Romney camp.

Among the other insights the Pew analysts surfaced was the tendency of the Obama campaign to target more precise voting groups in its online efforts than his opponent. They pointed out that invites visitors to join any of 18 specific consultancy groups, organized by category such as African Americans, women and Latinos.