Little candidates who could

There's also a wild card: Libertarian Rep. Ron Paul of Texas, who sought the GOP nomination and has continued to attract fervent supporters to his "Campaign for Liberty" attacking big government and the two-party system. After months of bickering with the Libertarian Barr, last week he threw his support behind yet another alternative party candidate, Chuck Baldwin of the Constitution Party. With Barr having raised nearly $1 million and becoming a growing presence in many states, adding a Paul-supported Baldwin to the mix could be disastrous for McCain, who could lose votes to both alternative candidates.

A third-party candidate in an election this close doesn't need double-digit support to be a spoiler. History has shown that third-party candidates can gain a large percentage, as in the case of Ross Perot, who reached close to 20% of the vote in 1992, and George Wallace, who almost gained 14% of the vote in 1968. But neither of those had the impact of Nader's single-digit percentage in the 2000 election. Nader's 90,000 votes in Florida were a crucial factor in an election that came down to George W. Bush's victory in Florida by slightly more than 500 votes.

To be clear, this election is coming down to the wire, as it did in 2000, making real the possibility of a third-party spoiler tipping the election one way or the other. As the polls stand now, with Obama holding slight leads nationally and in many swing states, Nader's 4% could siphon off enough votes to thrust McCain into the White House. That said, if Barr steals 8% of the Ohio vote from McCain, Obama will almost certainly win the presidency.

So in the waning days of the election, it's not the biggest poll percentages that demand scrutiny, but the smallest ones. Because it could turn out that the crucial role in the 2008 election will be played by a candidate no one is talking about.