The Democrat, who is on the verge of becoming the first black president of the US, stormed through Florida, North Carolina and Virginia – three states he is bidding to wrench from the Republicans – on the final day of his dramatic battle against John McCain.
“Virginia, let’s go change the world,” Mr Obama told more than 90,000 people at the end of his closing rally in Manassas.
“Fired up?” he demanded to know of the sea of supporters. “Ready to go!” they responded in a deafening roar.
But if the polls are correct and Mr Obama triumphs against McCain on Tuesday, the Democrat’s white grandmother Madelyn Dunham will not be there to see it.
The last survivor of the family that raised him died on Monday aged 86.
Mr Obama said the “unlikely journey” that started out 21 months ago was now on the cusp of remaking the stricken US economy, end the war in Iraq, take the fight to al-Qaeda in Afghanistan and restore the nation’s global leadership.
“That’s how we’re going to change this country, because of you,” he told the vast crowd, while urging his supporters on the campaign’s climax not to “slow down or sit back or let up, not for one hour, not for one second.”