Election Day often comes down to the results of a few crucial battleground states where key electoral votes can hold the key to the White House.
In 2000, that battleground was certainly Florida. In 2004, much of the election seemed to hinge on the results in Ohio.
This year, the campaigns are focusing their time and money on several critical states where the race is hard-fought. But with the election looming just a week and a half away, Democratic candidate Barack Obama has taken an increasingly commanding electoral-vote lead in eight critical battleground states that could decide the presidency.
ABC News has looked at several factors to assess how those electoral votes may fall on Election Day -- including reporting from the campaigns themselves, national party officials, outside groups, House and Senate party committees, state parties and polls. Analysis shows that Republican candidate John McCain's support in these states -- all of which went to George W. Bush in both 2000 and 2004 -- may not be enough.
On Wednesday, a top Republican campaign official told ABC News' George Stephanopoulos on the condition of anonymity that the Obama campaign is on a roll.
"This is the greatest ground game they've ever put together," he said. "It's scary."
Eight states that could go either way -- Ohio, Florida, Virginia, Colorado, Nevada, Missouri, Indiana and North Carolina -- hold 111 of the 270 electoral votes needed for either candidate to win the presidency.
Whether those red states will turn blue is yet to be determined, but according to the latest polls, Obama has a 52-45 percent advantage in those battlegrounds. States like Indiana, Missouri and North Carolina, previously leaning in McCain's favor, are now considered toss-ups.
With polls showing Obama leading in Colorado and Iowa, McCain needs to hold all the big states Bush won in 2004, plus capture a John Kerry state like Pennsylvania in order to win the presidency.
If this year's map breaks the way it did in 2004, then Obama would need to win only one of the red battleground states where he leads or is tied in polls with McCain. A victory in Virginia, Florida or Ohio would net Obama enough electoral votes to win the White House.
OHIO: 20 Electoral Votes
According to a Wednesday CNN/TIME/Opinion Research poll, Obama is up 50-46 in Ohio.
Voters in Ohio have selected the eventual winner in the past 11 presidential elections, and no Republican has ever won a presidential election without winning the state.
This election, economic discontent could be a decisive factor in that decisive race. With half a million Ohioans out of work -- the state's highest unemployment rate in 16 years -- and with the state also tallying the third-highest home foreclosure rate in the country, the latest ABC News/Washington Post poll of Ohio finds that the economy is the single most important issue to the state's registered voters.