President Barack Obama and opponent Mitt Romney have darted across the US in an 11th-hour blitz for votes ahead of Tuesday's election.
Headed into the last two days of a historically close presidential race, the candidates kept up a feverish pace on Saturday, making a total of seven campaign stops in a bid to capture every vote they can.
At one point, Obama and Romney appeared just a few kilometres from each other in Iowa, one of seven to 10 fiercely contested swing states that will decide who claims the White House on Tuesday (Wednesday, NZ-time).
While the candidates are nearly tied in national polling, Obama has a slight advantage in the battleground states.
The US president is decided not by the national popular vote but rather by a system of electoral votes assigned to each state based on their representation in Congress.
In all but two of the 50 US states, the winner of the presidential vote takes all of the electoral votes. To win, a candidate must secure at least 270 electoral votes. Obama is already assured of 243 votes in heavily Democratic states while Romney can claim 206, putting more pressure on the Republican challenger to win more of the swing states.
In Milwaukee, Obama had pop star Katy Perry - wearing a tight blue dress embossed with the Democrat incumbent's "Forward" slogan - warm up a crowd estimated at 20,000.
When the main act appeared, the tone was more like a bar fight than a pop concert. Obama hit out at what he said was Romney's plan to let Wall Street return to the days when it had "free rein to do whatever" it liked, which he said had led to economic woes "we're still cleaning our way out of".
"Governor Romney now is a very talented salesman," Obama said. "So in this campaign, he is trying as hard as he can to repackage the same old ideas that didn't work and offer them up as change."
The stakes in the 2012 presidential race are "a choice between two very different visions for America", Obama, 51, told cheering supporters at Mentor in Ohio.
"It's a choice between going back to the top-down policies that crashed our economy, or a future that's built on a strong and growing middle class."
Obama is planning to visit Ohio every day until the election - a sign of just how crucial the midwestern state is. No candidate since 1960 has won the White House without capturing Ohio.
A poll released on Saturday showed Obama with a six-point lead over Romney in Ohio. The poll by NBC News, the Wall Street Journal and Marist gave Obama 51 per cent support to Romney's 46 per cent in the state.
In Dubuque, Iowa, Romney charged that Obama had failed to work with Republicans and touted his election as a Republican governor in the heavily Democratic state of Massachusetts as evidence of his bipartisan approach.
In New Hampshire earlier in the day, Romney told supporters: "The question of this election comes down to this: do you want more of the same or do you want real change? President Obama promised change, but he could not deliver it. I promise change, and I have a record of achieving it."
The 2012 presidential election is expected to cost about US$2.6 billion, an actual decrease from the US$2.8 billion spent in 2008, according to the Centre for Responsive politics.