US President Barack Obama and Republican Mitt Romney have been again in the crucial battleground state of Ohio, with a special urgency for Romney as new polling shows the president edging ahead there less than a week before early voting begins.
A day after his address to world leaders at the United Nations, Obama was speaking at two universities in the Midwestern state, hoping to generate the kind of enthusiasm among young voters that helped fuel his victory four years ago.
Romney was making three stops in major cities during a bus tour aimed at drawing a contrast with Obama on the economy, which remains the top issue for voters before the November election.
Both candidates in the tight race recognise how critical Ohio's 18 electoral votes will be.
Time is running out
Losing the state would dramatically narrow Romney's path to the 270 state-by-state electoral college votes required to win the White House - and no Republican has ever lost Ohio and won the presidency.
With early voting set to begin in Ohio on October 2, time is running out.
The candidates are also preparing for their first of three debates next week, the next chance for Romney to make a high-profile, widely broadcast case for the presidency.
Obama's visit marks his 13th trip to Ohio so far this year, his campaign said. Romney has visited the state 10 times since May 1, his campaign said, with an additional seven visits during the earlier primary campaign.
The president has the edge in Ohio six weeks out from Election Day, helped by signs of an improving economy.
A Washington Post poll on Tuesday showed Obama with a lead in Ohio that was outside the poll's margin of error. Even on handling of the economy, where Romney until recently has had an advantage, Obama now leads.
A new CBS/New York Times poll also shows Obama ahead in the state and ahead in Florida, which along with Ohio is the most important of the 10 or so battleground states that will decide the election. Such states do not reliably vote Democrat or Republican and are the target of a dizzying amount of campaign ads.
The White House expressed confidence. "As time progresses, you know, the field is looking like it's narrowing for them," campaign spokeswoman Jen Psaki told reporters aboard Air Force One as Obama headed for Ohio. "And so in that sense we'd rather be us than them."
For Romney, Ohio was already challenging because of the state's better-than-average economy.
The jobless rate in Ohio stands at 7.2 per cent - almost a full percentage point lower than the national average. The good news hurts Romney's assertion that Obama's policies aren't working.
Romney warned at his first Ohio stop Wednesday that the nation's debt could grow to almost $20 trillion if the country re-elects Obama. The debt is now at $16 trillion and growing.
Trade policies with China
The candidates also exchanged attacks over trade policies with China, an issue for working-class voters whose livelihoods have been affected by competition from Chinese manufacturers.
"When people cheat, that kills jobs," Romney said at an Ohio rally Tuesday. "China has cheated. I will not allow that to continue."
Obama on Wednesday accused Romney of showing "newfound outrage" on cracking down on China, and Obama campaign spokeswoman Ben LaBolt criticized Romney's own investments in Chinese companies. "How can we trust Mitt Romney to stand up to China when he profits from China breaking the rules?" LaBolt said in a statement.
The Obama campaign said the president has brought more trade cases against China in one term than President George W. Bush did in two.
The Obama administration filed a complaint this month with the World Trade Organisation over Chinese subsidies to its auto and auto parts industries, the latest in a series of actions dating back to 2009 to protest what US manufacturers say are the unfair advantages China gives its own companies.
Romney has vowed to issue an executive order in his first day in office labeling China a currency manipulator, a designation that would trigger negotiations between the two countries and could ultimately lead to US trade sanctions against China.
The Obama administration has not been willing to take that step, which is opposed by the influential, non-governmental US Chamber of Commerce.
Working to close the gap in Ohio, Romney's campaign released a new ad Wednesday featuring Romney speaking to the camera and acknowledging his opponent's good intentions.
"President Obama and I both care about poor and middle-class families. The difference is my policies will make things better for them," he says.