Well now, let's be fair. He's a Democrat. No Democrat presidential candidate could ever hope to run a campaign on small donations, because there just aren't enough of them.
The Democrat constituency is, for the most part, the very very very poor and the very very very wealthy, with the former vastly outnumbering the latter. Obviously, the former cannot and will not donate to the Obamessiah's campaign, and the latter group is so small that, if they limited themselves to small monetary donations, they wouldn't have enough funds to throw a pizza party, let alone a presidential campaign.
A Republican candidate, on the other hand, can successfully campaign on donations averaging $50 a pop, simply because of the sheer number of donations they will recieve.