The Illinois senator said he admired a presidential candidate who said in 2000, "I will not take the low road to the highest office in this land."
"Those words were spoken eight years ago by my opponent, John McCain," Obama said. "But the high road didn't lead him to the White House then, so this time, he decided to take a different route."
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.
In Ohio's hard-pressed southeast, McCain whipped up a crowd of several thousand at the county courthouse in Steubenville, telling them, "You're going to be the battleground state again. You're going to be the one who decides. I need Ohio and I need you."
The candidate was running about an hour behind schedule but said waiting supporters bucked him up with their "enthusiasm."
"I know momentum and we've got it now in Ohio," McCain said.
In what could be a final ignominy for McCain, Obama campaign manager David Plouffe said the campaign would 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, and that the campaign was mounting ads in all three states. A recent poll from McCain's home state showed the two candidates in a statistical dead heat. (Read more in Horserace)
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 campaign manager Rick Davis derided Obama's moves: "We encourage them to pick other states that we intend to win" to spend their money.
The combined efforts of the McCain campaign and the Republican National Committee have been closing the advertising advantage that Obama has enjoyed since the two party conventions this summer. Davis said Friday that the latest push of McCain and party advertising will exceed Obama's spending in the final days of the campaign.
McCain pollster Bill McInturff also sounded an optimistic note, saying his surveys show Obama's support fading and McCain's increasing.
"We've shaken off the affects of the financial collapse," Davis said, blaming harsh news about the economy for Obama's leads in the polls.
While the Obama campaign continued to tie McCain to the unpopular President Bush, McCain assailed Obama's economic policies as recipes from the far left of American politics.
Earlier Friday, McCain told a rally in Hanoverton, Ohio, that Obama "began his campaign in the liberal left lane of politics and has never left it. He's more liberal than a senator who calls himself a socialist," a reference to Sen. Bernie Sanders, an independent from Vermont.
Campaigning with McCain was former GOP rival and one-time New York mayor Rudy Giuliani, who told the crowd, "John McCain was right about the single most important decision that had to be made in the last four years and that was to stick it out in Iraq."
McCain began the day with an interview on ABC's "Good Morning America," saying, "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 is proposing tax increases on families making over $250,000 and individuals making over $200,000 and tax cuts for the 95 percent of workers making less than $200,000.
In an interview with The Columbus Dispatch published Friday, Schwarzenegger made no effort to disguise the challenge facing McCain He told the newspaper it will be a "major struggle for him to win."
But, he added: "I have seen him in those major struggles in the past when he has come back when everyone counted him out," Schwarzenegger said. "During the primaries, he came back and got nominated."
Privately, McCain's aides said their man trailed Obama by 4 points nationwide in internal polling.
The latest CBS News/New York Times poll, released yesterday showed Obama ahead.
Obama was to spend the day campaigning across the Midwest, with a quick stop home in Chicago to see his daughters on Halloween.
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The Obama campaign plans to air two ads in Georgia and North Dakota - a tandem of positive and negative commercials.
One ties McCain to President Bush, showing a man adjusting a review mirror in a car as an announcer says: Wonder where John McCain would take the economy? Look behind you, John McCain wants to continue George Bush's economic policies."
The other relies on Obama's message of "unity over division" and reminds viewers that Obama has been endorsed by mega-financier Warren Buffett and former Secretary of State Colin Powell.
Plouffe said that in deference to McCain, the campaign would only run the positive ad in Arizona.
"It's Sen. McCain's home state," Plouffe said. "We're cognizant of that."