They've been at it for nearly two years. Now, the hours left in their epic campaign have dwindled to two digits.

John McCain and Barack Obama are using them to criss-cross the country making their final arguments to voters, who have been the targets of the longest, most expensive and, arguably, the most unpredictable campaign in American history.

The Republican McCain vowed that that unpredictability would continue through Tuesday with a historic upset, defying polls and circumstances that allowed his opponent, while warning against complacency, to suggest that he feels "a righteous wind" at his back.

In pursuit of another Dewey-Defeats-Truman moment, Mr. McCain continued to focus on Pennsylvania while continuing to play defense in a slew of normally Republican states where he appeared to be trailing the freshman senator from Illinois.

Reflecting the confidence of the Democratic campaign, Mr. Obama was spending his increasingly scarce campaign time in states that President Bush won four years ago, pressing home his argument that his opponent, while calling himself a maverick, offers little more than an extension of the Bush administration.

Campaigning in Virginia, one of the Bush states in which Mr. Obama's polling has topped 50 percent, Mr. McCain tried to raise doubts about his opponent by seizing on the Democrat's observation the previous day in Iowa, that his breakout victory in the state's caucuses had vindicated his faith in America.

"My country has never had to prove anything to me, my friends," Mr. McCain said. "I've always had faith in it and I've been humbled and honored to serve it."

Obama spokesman Bill Burton released a statement blistering the Republican's comparison.

"It's pathetic that John McCain would take a statement Barack Obama has been making for a year about his faith in the American people and distort it to attack his patriotism,'' Mr. Burton said. "Sadly, this is what we've come to expect from a desperate, dishonorable campaign.''

From Virginia Mr. McCain headed to a rally in Bucks County outside Philadelphia. After a detour to New York City for an appearance on "Saturday Night Live," the GOP nominee planned to return to the state today for appearances in Scranton and Delaware County.

The Bucks and Delaware county stops would continue his focus on the vote-rich and once reliably Republican Philadelphia suburbs that have trended Democratic over the last decade.

The Republican hopes to boost his southwestern Pennsylvania turnout tomorrow with yet another appearance at an airport hanger in Moon, less than a mile from the site of a similar appearance earlier this month at Robert Morris University.

The Democratic vice presidential nominee, Sen. Joseph R. Biden Jr., was to be in Philadelphia tomorrow night, but as of yesterday, Mr. Obama had no plans to return to a state in which he has enjoyed a strong polling lead for months.

Mr. Obama's decision to forgo 11th-hour campaigning in the state could be seen as a sign of his campaign's confidence in his standing here. But the Obama forces continued to pour dollars into the state's television markets and were embarked on a last-minute get-out-the-vote drive that Gov. Rendell has described as unprecedented in the state's political history.

While several surveys in the last week did show some narrowing in his margin here, an aggregate of results compiled by the Web site pollster.com continued to show Mr. Obama with a nine-point Pennsylvania advantage and with his average poll number above 50 percent.

The McCain campaign remained intent on overcoming those odds, however, to balance the likelihood that his opponent would capture other states that contributed to Mr. Bush's 2004 total of 286 electoral votes.

If, for example, Mr. Obama were to capture New Mexico, Colorado and Iowa -- all states in which the Democrat is now leading -- Pennsylvania would be a vital counterweight to their combined Electoral College total of 21.

Mr. Obama appeared in Colorado, Nevada and Missouri yesterday, all states won by Mr. Bush four years ago. At a stop in Colorado, he took as a rhetorical gift a statement from Vice President Dick Cheney, who in a rare campaign appearance in Montana praised the Republican nominee.

"Earlier today, Dick Cheney came out of his undisclosed location and hit the campaign trail,'' Mr. Obama reported. "He said that he is, and I quote, 'delighted to support John McCain.'

"I'd like to congratulate Sen. McCain on this endorsement because he really earned it," Mr. Obama added, according to the prepared text e-mailed by his campaign. "That endorsement didn't come easy. Sen. McCain had to vote 90 percent of the time with George Bush and Dick Cheney to get it. He served as Washington's biggest cheerleader for going to war in Iraq, and supports economic policies that are no different from the last eight years."

While Mr. Obama and Mr. McCain spoke to cheering crowds, their ground troops began the final drive to mobilize their voters. In this potentially crucial area, the amply funded Obama campaign is acknowledged even by most Republicans to hold an advantage.

Throughout the primaries and caucuses, the Illinois senator's campaign established a track record of voter registration and get-out-the-vote logistics perhaps unprecedented in modern campaigns.

Their only rival for that accolade may have been the Bush-Cheney effort in 2004. In a conference call with reporters Friday, Republican aides maintained that their rate of voter contacts was actually ahead of the pace that the GOP campaign recorded four years ago, but in numbers of offices, paid staff and volunteers, their logistical push appeared to be dwarfed by the Democrats.

Polls have also consistently found a Democratic advantage in the proportions of McCain and Obama supporters who say they are enthused about their candidate.

Some combination of enthusiasm and fieldwork appeared to be evident in the strong, in some places, record rates of early voting occurring in the 32 states that allow no-excuse voting before the traditional Election Day.

No one knows the tally so far, but the party affiliations recorded, and the demographic backgrounds of early voters found in polling, led the Democratic campaign to suggest that Mr. Obama would go into Tuesday with a substantial head start in crucial swing states.

In a call with reporters, David Plouffe, the Obama campaign manager, maintained that to overcome the early votes already banked, Mr. McCain would need to win significantly more than 50 percent of Tuesday's ballots to achieve overall majorities in many early voting states.

In a memo widely distributed Friday, McCain campaign manager Rick Davis, disputed that analysis.

"The facts undermine their argument,'' he said. "In our analysis of early voting and absentee votes to date: The composition of the electorate has not changed significantly and most folks who have voted early are high-propensity voters who would have voted regardless of the high interest in this campaign.''

In a call to reporters Friday, and in a recent memo from its pollster, Bill McInturff, the McCain campaign cited progress in its national numbers. But one neutral polling expert saw a more static picture continuing to favor the Democrat.

"Not surprisingly, yesterday was another heavy day of new poll releases: 37 new statewide surveys and 10 national releases," Mark Blumenthal wrote in a weekend analysis on the web site pollster.com "Yet these surveys indicate no clear trends and leave our bottom line electoral vote count unchanged. McCain does a little better on some polls and on some of our statewide trend estimates, Obama does a little better on others. The net result -- for today at least -- looks mostly like random noise.

"Yesterday's new national poll releases, however, provided no good news to those looking for a late shift to Mr. McCain. Mr. Obama's margin on our national trend estimate clicked up slightly yesterday (to +6.0) for the first time in a week."

Mr. McCain's planned airport rally Monday will be roughly his 20th appearance in Pennsylvania since the spring, far more than his rival's total. Mr. Obama has made two appearances in the state since the final presidential debate. Mr. McCain and his running mate have practically camped out here. Pennsylvania has also been consistently near the top of the McCain list for television advertising.

The Wisconsin Advertising Project, which tracks media spending across the country, reported that from Oct. 21 to Oct. 28, the McCain campaign, along with coordinated GOP spending accounted for roughly $1.39 million on Pennsylvania television, just a shade behind its spending in Florida. The Obama campaign, however, poured $2.7 million into the state.

Overall in those seven days, the Democratic campaign outspends its rival by a margin of about 3-to-2 on television. Florida spending provided a prime example of the financial edge Mr. Obama reaped by opting out of the federal financing system. There, while, the McCain forces were spending $1.4 million, the Democrat poured in $4.6 million.

In the face of the Obama ground game, Republicans continued to try to exploit Democratic fissures remaining from a drawn-out primary in which Mr. Obama was beaten by Sen. Hillary Rodham Clinton by nearly 10 points. In one mail piece, the GOP featured a picture of Mr. McCain and Mrs. Clinton smiling together and trying to associate the Republican "as the father of three daughters'' with Mrs. Clinton's "18 million cracks in the glass ceiling.''

Separately, the Republican State Committee announced that they would sponsor television ads reminding voters of Mr. Obama's association with his former pastor, Rev. Jeremiah Wright. A state committee official said the ad would air on "network television,'' but did not release any details on the extent of their buy.

While frequently raising questions about other Obama associations, notably the former Weather Underground figure, William Ayers, Mr. McCain's own campaign has avoided mention of the sometimes-incendiary remarks of the Rev. Wright. In the spring, Mr. McCain had urged North Carolina GOP officials to pull a similar ad.

Asked to comment on the state committee's plans yesterday, McCain spokesman Paul Feldman said, "John McCain's position with respect to Reverend Wright is clear. He is not the referee of every political ad in this election."