AS BARACK Obama took the podium before 27,000 cheering supporters at Cincinnati's Nippert Stadium, he was so tired that just speaking looked like a Herculean effort. His usually rich baritone sounded weak and reedy as he stumbled over the names of local worthies and garbled phrases from his stump speech he has repeated hundreds of times.
As Mr Obama spoke, senior staffers stood nearby, leaning against anything they could find to stay upright, struggling to keep their eyes open after weeks of sleeping three or four hours a night. Despite his exhaustion, Mr Obama seemed cheerful as he looked out on the vast crowd in Ohio's Hamilton County , traditionally solid Republican territory in the state that swung the 2004 presidential election to George Bush.
When part of the crowd started to boo at the mention of the president's name, Mr Obama raised his hand.
"You don't need to boo," he said. "You just need to vote."
Much of Mr Obama's speech was a sustained assault on John McCain but even the barbs were delivered with a shrug or a smile.
He said that, while Mr Bush was sitting out the last days of the election, vice-president Dick Cheney had emerged from his "undisclosed location" to endorse Mr McCain.
"Here's my question for you, Ohio: do you think Dick Cheney is delighted to support John McCain because he thinks John McCain's going to bring change? Do you think John McCain and Dick Cheney have been talking about how to shake things up, and get rid of the lobbyists and the old boys club in Washington?" he said.
"George Bush may be in an undisclosed location, but Dick Cheney's out there on the campaign trail because he'd be delighted to pass the baton to John McCain. He knows that with John McCain you get a twofer: George Bush's economic policy and Dick Cheney's foreign policy - but that's a risk we cannot afford to take."
Mr Obama said that Mr McCain had spent the last few weeks of the campaign "calling me everything except a child of God" but promised that a Democratic victory today will end negative politics "once and for all".
Ohio can be a tough state for Democrats, as John Kerry discovered in 2004 after what looked like one of his party's most successful presidential campaigns ever in the state. For decades, Democrats have used a rule of thumb to calculate how they were doing in Ohio's statewide races: if the Democrat wins the industrial area around Cleveland by at least 150,000 votes, loses the conservative region around Cincinnati by less than 60,000 and plays about even around the state capital of Columbus , he almost always wins.
Mr Kerry exceeded all those benchmarks and turned out more Democrats than ever before but Mr Bush won the state by running up his numbers in suburban and rural counties. Two years later, Democrat Ted Strickland was elected governor after using a new strategy - maximising the Democratic vote but supplementing it by picking up as many votes as possible in traditionally hostile parts of the state.
Mr Obama's campaign has adopted Mr Strickland's approach and the Cincinnati rally served not only as a morale booster for supporters but as an organisational element in the voter turnout effort. Everyone who entered the stadium gave the campaign their names, addresses, phone numbers and email addresses; this morning, each one will receive calls, emails and text messages telling them where to vote and where they can be useful as volunteers on Election Day.
"It's amazing. So many people are volunteering, making calls, walking around neighbourhoods, setting up signs," says Barbara Schwam, a social worker who supported Hillary Clinton in the primaries but is now fully on board for Mr Obama. "We work as hard as we can."
Ms Schwam is confident that Mr Obama's appeal, his ground operation and the popular appetite for change will deliver a Democratic victory today but Tracy Watson, a patient care assistant at the local children's hospital, is more wary. "I still think that anything can happen," she says. An African-American, Ms Watson believes Mr Obama would unite the country and improve everyone's life but she won't be shocked if Mr McCain wins. "We're used to the struggle so it would be just the same, we'd just probably have to struggle a little harder," she says.