With 2.3 million unique visitors, Obama's campaign Web site drew four times as much traffic as McCain's in May, the final month of the Democratic primary season, according to Nielsen Online.
Obama also won the battle for online buzz, with double the proportion of blog mentions, at 0.75% to McCain's 0.39%.
In the Internet ad arena, display ads run by the Obama campaign in May had 105.6 million impressions compared to only 8.5 million for McCain's. However, the presumptive Republican nominee led in impressions on sponsored search links, with 5.4 million to his Democratic counterpart's 1.8 million.
Whether McCain will be able to narrow the online gap during the general election campaign remains to be seen. "Obama has been extremely aggressive online," said Jon Gibs, vice president of media analytics at Nielsen Online. "It will be interesting to see if McCain follows suit, and if he's able to give the infrastructure he's put in place."
Even if McCain does make a bigger Internet push, there's still a question as to whether it would increase his support among older voters that help make up his core demographic, Gibs said. McCain didn't help efforts to upgrade his standing as a Web-savvy candidate when he admitted recently to being computer illiterate.
And McCain Internet strategist Mark Soohoo only seemed to make matters a worse when he reassured audience members at the Personal Democracy Forum a couple of weeks ago that "John McCain is aware of the Internet," and that it would be wrong "to assume John McCain has no knowledge of this."
Regardless of how many Facebook friends McCain has compared to Obama, recent polls indicate he's not getting blown away by his Democratic rival. A Gallup daily tracking poll released July 7 gave Obama a 47% to 43% edge over McCain. A Rasmussen Reports poll yesterday had Obama ahead 46% to 41%.
Further, the Nielsen data showed that registered voters who are Internet users are almost evenly divided between Democrats and Republicans at 35% and 36%, respectively. Independents account for 17%. Nearly 89% of active Web users overall are registered to vote.
The breakthrough this year in online politics hasn't been so much in ad spending, but in voter engagement, according to Gibs. "Ad spend isn't really the yardstick we want to be using," he said. "Consumer engagement with the medium ends up being a much better story about power of the Internet."