Obama leads Romney in new polls

Obama also led a Gallup daily tracking poll by six per cent and is up in the top nine battleground states, according to averages of recent polling the RealClearPolitics website. (AAP)

Obama also led a Gallup daily tracking poll by six per cent and is up in the top nine battleground states, according to averages of recent polling the RealClearPolitics website. (AAP)

Polls showing a widening lead for US President Barack Obama has piled more pressure on over presidential hopeful Mitt Romney.

A flurry of polls showing widening leads for US President Barack Obama has heaped pressure on Mitt Romney to use their first head-to-head debate next week to launch a major comeback bid.

Fresh surveys on Wednesday showed Obama cementing his advantage in the key state battlegrounds that will decide the US election on November 6, and putting clear distance between himself and his Republican challenger nationwide.

Romney's fading numbers appeared to reflect damage from the release last week of a secretly filmed video in which he said 47 per cent of Americans would vote for Obama because they were dependent on government and paid no taxes.

The former Massachusetts governor softened his tone on Wednesday, saying his "heart aches" for people struggling to find work and the government "has a role" in taking care of people who are hurting.

But he added: "we're going to insist these people have the opportunity for work if they can - if they're able bodied - because we're not going to create a society of dependence on government".

Both men duelled for votes of blue-collar workers in the key swing state of Ohio on Wednesday.

Romney appeared with local and golf legend Jack Nicklaus, while Obama mocked his foe's vow to stand up to Beijing, accusing him of investing some of his personal wealth in firms that outsource jobs there.

"When you hear this newfound outrage, when you see these ads he's running promising to get tough on China, it feels a lot like that fox saying, 'You know, we need more secure chicken coops'," he said.

"I mean, it's just not credible."

Romney lambasted Obama for failing to prevent the loss of 582,000 manufacturing jobs in the past four years and placed much of the blame on "competition from overseas, which is often unfair".

"From day one I will label China as a currency manipulator," Romney told supporters.

"They must not steal jobs."

Romney also insisted "we're going to win Ohio," despite a Quinnipiac University/New York Times/CBS News poll on Wednesday showing him down 10 points in a state no Republican has ever lost and still won the White House.

A Washington Post poll put Romney's deficit in the state at eight points.

The Quinnipiac poll also showed Romney down by nine per cent in the biggest battleground state Florida, completing a scenario that would deny the Republican a credible route to the White House.

Obama also led a Gallup daily tracking poll by six per cent and is up in the top nine battleground states, according to averages of recent polling the RealClearPolitics website.

Neither campaign expects Obama to win Ohio and Florida by such wide margins in November.

But the new polling data added to growing signs that Romney would have to pull off a stunning comeback to win the White House.

His best chance to change the narrative may be in the first of three presidential debates, in Denver, Colorado, on October 3.