As of early October, national polls and the electoral map are leaning towards Barack Obama.
Obama needs to hold all the states John Kerry, the 2004 Democratic presidential nominee, won plus win one with lots of electoral votes, like Ohio or a couple of states with more modest electoral votes, like Virginia and Colorado.
McCain needs to hold almost all the states Bush won in 2004. If he loses a smaller state like Iowa to Obama, McCain can still win if the South and Mountain West stay in the Red column.
Polls indicate the swing states are changing. Obama's support in Michigan is strengthening, and John McCain has pulled out his resources. New Hampshire has also moved towards Obama.
Right now there are eight battleground states: Ohio, North Carolina, Missouri, Indiana, Florida, Virginia, Colorado, and Nevada.
This list may shrink or grow in the last few weeks of the campaign.
Importantly, many of these battlegrounds are rich in electoral votes. Florida alone contains 10 per cent of the electoral votes needed to win, and a loss there will be very hard to mitigate against.
Voter registration in most states is coming to an end. The pool of potential participants is set, and it looks good for Obama.
The campaigns must now sway the undecided voters and encourage all registered voters to go to the polls on November 4th.
In many states, many more Democratic voter are registered, a good sign for Obama.
Electoral votes: 9
Colorado is a Mountain West state that has been solidly Republican for years. This time though, the Democrats believe they can put it in the Blue column.
Changing voter demographics, the Democrat's National Convention, and a concerted effort by Obama have contributed to putting the state in play.
Electoral votes: 27
Florida, Florida, Florida. It's a big, diverse state, with large elderly and Hispanic populations.
Florida won the presidency for George Bush in 2000 and went for Bush again in 2004, but now Obama's numbers are up.
Electoral votes: 11
It's been a solid Republican state for 40 years but right now it's too close to call.
Indiana borders Obama's home state of Illinois and is being barraged with Obama ads.
Electoral votes: 11
Missouri is an important bellweather state. It has voted for the winning candidate in every election for 100 years, except one.
Electoral votes: 5
Nevada is a Mountain West state and likes to vote for the winners. It has correctly predicted the winner of the White House since 1980.
It leans Republican, but right now, Vegas gambling houses are giving better odds on Obama than McCain.
Electoral votes: 15
Barack Obama is pouring in resources to try to pull out a Southern Republican state.
More than 400,000 people have registered to vote this year, and the majority of them are Democrats. But North Carolina hasn't voted for a Democrat since 1976.
Electoral votes: 20
Ohio is big, economically depressed, and a true indicator of the national mood.
No Republican has won the White House without Ohio. Obama is up in some polls, but both candidates are fighting hard.
Electoral votes: 13
Virginia is Obama's best chance to break the Republican hold on the South.
The state has voted for the Republican ticket since 1968, but changing demographics, a popular Democratic governor, and a blitzkrieg by the Obama campaign have put it in play.
Source: Al Jazeera