I think Biden spoke a little too quickly when he said that Obama was articulate. Obama may have an affirmative action degree from Harvard, but he talks like Jesse Jackson - and says stupid things dressed up with pretty words.
Obama headed the Harvard Law Review while he was there, which means he was considered by his peers to be among the elite... Obama is not only articulate, he is intelligent-- despite being well to the left of even Hillary, he's convinced a great many people that he's a "moderate" who can "heal the divide". The fact of it is, the Left tends to have many of the smartest people on its side--- dreams of planned economies and the like often flatter their notions of themselves, as Thomas Sowell has noted.