What do these three individuals have in common? They use an aggregation of poll results to estimate the probability that Obama will win the election in November. They all focus on the electoral vote because in the US the states decide who wins the election, the popular vote, i.e. the percentage of people from the whole country who vote for one or the other candidate does not matter.
Tom uses straight-forward arithmetic and poll results including those from the right-leaning Real Clear Politics web site for his prediction. As of Nov 3rd, he predicts that Obama will win at least 303 electoral votes which are 33 more than he needs to win the election.