The John McCain-Barack Obama election looks like one of the clearest choices in years, but history also shows that presidential contests rarely unfold along logical paths.
The competition at first glance is a study in contrasts.
McCain is 71, a Vietnam War veteran who's trying to become the oldest person ever elected to a first term.
Obama's 46, a native of Hawaii and a one-time Chicago community organizer who's trying to become the first black person to win the White House.
McCain is a usually loyal Republican with an independent streak; he's voted with his party 88.3 percent of the time in the current Congress, well above his Republican colleagues' average. He likes the idea of making President Bush's tax cuts permanent and thinks that the Iraq war remains a vital U.S. interest.
Obama is a fiercely loyal Democrat with his own independent thoughts. He's voted with his party 96.4 percent of the time since January 2007. He regards the Iraq war as a mistake and wants to cut taxes for the middle and poorer classes while raising them for the wealthy.
McCain is a 25-year veteran of Congress. Obama's been in the Senate only 31/2 years, and a lot of that time was spent campaigning for the White House – and missing votes.
Both candidates face problems. Both still need to unify their parties. Obama lost most of the year's big battleground states in Democratic contests and did poorly among older white voters, many of whom have said they'll give McCain a look.
McCain, though, still isn't the darling of his party's conservative wing; long after his major rivals left the race, he rarely got more than 75 percent of the Republican primary votes in late spring primaries.
Both also are fighting history, which shows that November voters don't simply go down checklists and contrast candidates' stands on policy questions. Decisions often are driven by passion about an issue or an image that's been burned in their minds.
Obama will pound home the idea that “a vote for McCain will be seen as a public acceptance of the idea we can stay there (in Iraq) awhile,” said John Fortier, a political analyst at Washington's American Enterprise Institute, a center-right research center.
“The war was his launching pad during the primaries,” said Carl Pinkele, a professor of politics at Ohio Wesleyan University. “It should continue to be a strong asset.”
Yet Obama and McCain are close in most national polls. Gallup's daily tracking polls have had them in a virtual tie for the past week.
Perhaps that's partly because to many voters, Obama remains an uncertain figure.
In contrast, “McCain can pull out his record and show where he has clear positions,” said Julian Zelizer, a professor of history and public affairs at Princeton University.