Springfield, Va. ? Warmed by the cheers of thousands, John McCain and Barack Obama plunged through the final weekend of their marathon race for the White House, the Republican digging for an upset while his confident-sounding rival told supporters, “We can change this country.”

“Yes we can,” Obama said, his slogan across 21 months of campaigning.

Both candidates were backed by legions of surrogate campaigners, door-to-door canvassers and volunteers at phone banks scattered across the country as they made their final rounds Saturday in a race that carried a price tag estimated at $2 billion.

Obama, ahead in the polls, maintained stride despite news that an aunt from Kenya, Zeituni Onyango, lives in the U.S. illegally. The Democratic candidate “has no knowledge of her status but obviously believes that any and all appropriate laws be followed,” said a written statement given to The Associated Press, which reported the story.

Campaign strategist David Axelrod added, “I think people are suspicious about stories that surface in the last 72 hours of a national campaign.”

McCain made no mention of Obama’s relative, but he worried aloud about the consequences of Democrats winning the White House while maintaining control of Congress. He warned of an agenda that “apparently … starts with lowering our defenses and raising our taxes.”

He contended that Obama was “running for redistributor in chief, I’m running for commander in chief.”

The Republican spent much of the day in Virginia, trying to make up ground in a state that has not voted Democratic since 1964 but leans that way now. “We’re a few points down, but we’re coming back,” he said. “I’m not afraid of the fight, I’m ready for it and you’re going to fight with me.”

Obama was in Nevada, then Colorado and Missouri, all states that voted for President Bush four years ago. Obama’s visit to Colorado marked his sixth trip to the swing state since he clinched his party’s nomination in June.

“We have a righteous wind at our back,” he told one audience.

When Obama arrived in Pueblo, Colo., his family was waiting for him on the tarmac, wife Michelle and daughters Malia and Sasha. Obama kissed his wife, hugged his daughters.

“We are three days away from bringing fundamental change to the United States of America,” Obama said. He told the crowd not to let up. “Not when so much is at stake,” he said. “We’ve got to win Colorado, and we’re going to win this election.”

Obama, bidding to become the nation’s first black president, led in national polls as well as surveys in several battleground states. McCain’s hopes of an upset hinged on winning all or nearly all the states that carried Bush to victory in 2004, and possibly carrying Pennsylvania to give him a margin for error.

As he stepped off his plane in Missouri, Obama was asked if he was worried about tightening polls.

“I never worry about the polls. Should I worry about the polls?” he said teasingly.

Campaigning in Missouri became a family affair for Obama, who appeared on stage with his wife and daughters before tens of thousands gathered on a high school football field in Springfield, Mo. The location was in Green County, where 62 percent of voters cast ballots for Bush four years ago.

“After eight years of failed policies from George W. Bush,” Obama started, sparking a chorus of boos from the crowd at the president’s name. “We don’t need to boo, we just need to vote,” he responded.