McCain was spending a second straight day touring economically ailing Ohio, a swing state with 20 electoral votes that McCain aides acknowledge is central to a victory on Tuesday. McCain was behind Obama in polls in the state.
"We're going to fight it out on the economic grounds," McCain told ABC's "Good Morning America."
"Sen. Obama's economic policy is from the far left of American politics and ours is in the center," McCain said. "He wants to raise people's taxes - that's clear."
Obama maintains that families making under $250,000 a year and individuals under $200,000 annually would not see any tax increase if he were president.
Obama's campaign, capitalizing on his vast financial resources and a favorable political climate, announced Friday that it was going back up with advertising in Georgia and North Dakota, two Republican states that it had teased with ads earlier in the general election campaign but then abandoned.
In what could be a final ignominy for McCain, Obama campaign manager David Plouffe said the campaign would also begin airing ads in Arizona, a state McCain has represented in Congress for 26 years. Plouffe said the race has tightened in Arizona, Georgia and North Dakota.
In a slew of states, "the die is being cast as we speak," he said. "Sen. McCain on Election Day is not just going to have to carry the day, but carry it convincingly."
McCain is planning a midnight rally on Monday in Prescott, Ariz., and his election party Tuesday night in Phoenix.
McCain was scheduled to campaign Friday in Hanoverton, Ohio, and in Columbus with California Gov. Arnold Schwarzenegger.
Obama was set to spend the day on a campaign crush across the Midwest, with a quick stop home in Chicago to see his kids. He makes his first stop back where his run began, in Des Moines, Iowa, where he upset Hillary Rodham Clinton in the campaign's first contest.
Independent polling in Iowa shows Obama consistently ahead in the race for the state's seven electoral votes, but McCain's campaign maintains the race is actually tighter than it appears.
After stopping at home for Halloween, Obama heads for a rally in Highland, Ind., a town in Democratic-dominated Lake County where Obama hopes to run up the vote to offset Republican domination elsewhere in Indiana.
Sprinting into the weekend, Obama was headed to the West, hoping to claim Colorado and maybe more. McCain was flying to Virginia, usually friendly country for the GOP but another place where polls give Obama the edge. McCain aides said the Arizona senator was likely to swing west also, to play to his base. A recent poll from McCain's home state showed the two candidates in a statistical dead heat.
There was nothing complicated about their closing arguments to voters, with the economy the top concern. Obama focused Thursday on linking McCain to Bush and blaming both for the nation's economic woes.
"John McCain has been right next to George Bush," Obama argued. "He's been sitting there in the passenger seat ready to take over every step of the way."
McCain had hoped the election would turn on issues like the Iraq war, where he could use his military background to convince voters he's the best choice as commander in chief. But he effectively has conceded that it's all about the economy and people's financial struggles.