Mitt Romney on the up in Iowa while Barack Obama attacks him over Big Bird

Republican candidate riding high after TV triumph with polls showing major gains

Energised by polls putting him in the lead not just nationally but in some battleground states too, Mitt Romney rumbled into rural Iowa yesterday to harvest votes in the state that kicked off the Republican nomination race back in January and set Barack Obama on course for the White House early in 2008.

If the boost from last week's debate in Denver has cheered the Romney camp, his supporters are feeling it too. Michael Jackson, 49, a welding shop owner who came to a family farm here in Van Meter to see the candidate pitch for the farming vote, predicted an easy win for the Republican in November. "By an avalanche, by an avalanche!" he declared, dismissing Mr Obama as "anti-God and anti-American".

On a blustery stage against a backdrop of a corn silo and combine harvester a few miles from John Wayne's birthplace, Mr Romney shared his new-born confidence, promising to take steps to help American farmers, including eliminating death taxes to help farmers pass on their land to their children and pursuing new trade deals. "The President has signed no new trade agreement with any nation around the world," he said.

"If I become President – sorry, when I become President – I will do everything in my power to strengthen once again the American farm," said Mr Romney.

Shaking up the race is a Pew Research Center poll released on Monday that showed a huge post-debate swing of 12 points for Mr Romney, putting him four points ahead of the President nationally by 49 per cent to 45 per cent. A poll by ARG last night showed him taking a one-point lead in Ohio and overtaking Mr Obama in Colorado. Both men were headed to Ohio last night.

The Obama campaign yesterday released a TV ad mocking Mr Romney for declaring at the debate that he would end subsidies to the Public Broadcasting System, the home of Big Bird and Sesame Street. After ticking off corporate crooks like Bernie Madoff, it turns to the feathery star. "Big, yellow, a menace to our economy, Mitt Romney knows it's not Wall Street you have to worry about, it's Sesame Street," the voiceover intones. "Mitt Romney taking on our enemies, no matter where they nest."

Yesterday Mr Romney fired back. "Gee, you have to scratch your head when you have an American President talking about saving Big Bird," he declared, suggesting to laughter that the President should be talking about "saving jobs and saving America".

Iowa may yet be tough for Mr Romney. In early voting, registered Democrats accounted for nearly two-thirds of the 110,000 ballots already cast by last weekend. The only poll here since the debate showed Mr Obama holding on to a slim 2 per cent lead. But analysts warn the support Mr Obama received in rural areas here and across breadbasket states of the Midwest four years ago has waned.

As well as being a swing state, Iowa has a psychic importance as the state that traditionally launches the nominating process before each election. No one here forgets that it was the Hawkeye state that gave first victory to Mr Obama in 2008 in the primary race against Hillary Clinton.

"Because we're the state that launched him, we feel the disappointment in this President more personally and intensely than anywhere else. Many Iowans want their votes back," David Kochel, Mr Romney's campaign chief in Iowa, noted.