Reply #6: It's the the fact that he keeps saying things such as this:

[Lone_Star_Dem]

"More and more people are asking, 'What about Al Gore?' " says Steve Grossman, former chairman of the Democratic National Committee. "If Al Gore were to announce for president, he would be a first-tier candidate on day one. Instead of it being Hillary and Obama on the covers of the national magazines, you would have three faces there."

The Internet activists would turn cyberspace into a potent fund-raising realm for Gore if he does decide to get in, Grossman predicts.

Publicly, Gore hasn't ruled out running, but neither has he evinced much interest.

But when one friend asked him recently about another campaign, Gore didn't dismiss the question out of hand. "We'll see how things go," he replied.
http://www.boston.com/news/globe/editorial_opinion/oped/articles/2007/01/16/another_chance_for_gore/