Even so, figures in the candidates' latest spending reports covering January underscore the gap in their online efforts. The Obama campaign paid more than $89,000 to Google and $18,252 to Microsoft for online advertising and a total of $32,372 to Yahoo and Yahoo Search Marketing. Obama paid another $23,564 to Yahoo subsidiary Right Media, an online ad exchange which handles mainly remnant advertising.
A further $1,821 went to Facebook, where Obama has attracted more "friends" than any other candidate, and $88,540 went to political consulting firm Blue State Digital.
The Clinton campaign, by contrast, reported only a $13,674 payment to Google during the same period.