The 47-year-old Obama struck an optimistic tone in an article published in the Wall Street Journal newspaper on Monday, concentrating on the historic nature of his campaign to become the first black US president.
"This is a defining moment in our history," Obama wrote.
"Tomorrow, I ask you to write our nation's next great chapter... If you give me your vote, we won't just win this election - together, we will change this country and change the world."
"After decades of broken politics in Washington, eight years of failed policies from George Bush, and 21 months of a campaign that has taken us from the rocky coast of Maine to the sunshine of California, we are one day away from change in America," Obama added in his forst speech in Jacksonville, Florida.
McCain, a 72-year-old former prisoner of war in Vietnam, has remained defiant.
"There's one day left until we take America in a new direction," McCain told a crowd of about 500 people in Florida early on Monday.
"The pundits may not know it and the Democrats may not know it but the 'Mac is back' and we're going to win this election."
Obama is holding a one percentage point lead in Missouri and a two point lead in Florida, according to the Reuters/Zogby polls.
Obama also held leads in Ohio, Virginia and Nevada - all states won by George Bush, the current US president, in 2004.
The five states where Obama is ahead, according to the polls, have a combined 76 electoral votes.
Taken along with the states won by John Kerry, the defeated Democratic candidate in 2004, Obama would have 328 electoral votes.
Obama also leads by 11 points in Pennsylvania, which McCain has targeted as his best chance to steal a state won by the Democrats in 2004.
The Illinois senator also holds a seven-point lead among likely US voters in a separate Reuters/C-SPAN/Zogby national tracking poll, up one percentage point from Sunday.
Under the US political system, the president is elected not by direct popular vote but by capturing 270 out of 538 electoral votes distributed throughout the country in a state-by-state contest.