Edwards, campaigning in the state that will hold leadoff caucuses in January, said his organization is much stronger than at this point in 2004 when he eventually won a surprise second-place finish.
Clinton now leads in Iowa as well as nationally, according to the latest polling. The Des Moines Register on Sunday had her at 29 percent in the state, up from 21 percent previously, with Edwards at 23 percent, down from 29.was at 22.
Asked about a belief among some that a Clinton nomination is inevitable, Edwards brushed the idea aside.
"I lived through the inevitability of Howard Dean," he said.
Dean, now chairman of the Democratic National Committee, was the front-runner in polls and fundraising in the 2004 election cycle before finishing third in the Iowa caucuses behind John Kerry and Edwards.
"I know that what happens, from my experience in 2004, is people look much more intensely at you as a candidate the closer you get to the caucus," he said. "A lot of the celebrity fades away. So, I think as a practical matter, that bodes well."
Edwards has increased the intensity of his criticism of Clinton in recent days, and his wife was asked about that in an interview on National Public Radio's "All Things Considered."
When Edwards was a boy, said Elizabeth Edwards, his father told him that if he was in a fight and had to hit back, "aim for the nose; you sort of get more bang for your buck there."
"So you have to aim for their vulnerability and make them understand that there is a cost associated with attacking you," Mrs. Edwards said. "You're not going to lay down. You're strong enough not only to take it but to hit back. It gives you an opportunity, I think, when you're fighting on even ground to redirect the conversation to something more productive for voters."
The candidate himself, speaking to reporters after an event in south-central Iowa, said he thinks about half of Iowans are still undecided.
Edwards was wrapping up a four-day, 17-county swing through Iowa. The trip was largely aimed at rural Iowans, and he spoke about aiding family farms, extending technology into all corners of the country and offering incentives to attract top teachers throughout the country.
"We need a president who instead of standing up for these big, corporate farming corporations, actually stands up for the family farmer," he told a crowd of more than 150 people in Corydon, a town of about 1,600.
Organizers there said Edwards was the first of the front-runners to visit Wayne County, where he spoke at a museum featuring old farm implements.
Edwards called for creating up to a million new jobs by making the country more energy independent with cleaner alternatives to oil. "A lot of those jobs ought to be in rural America," he said.
He blamed the Bush administration for the number of Americans who struggle to make ends meet and said, "We have the worst economic equality in this country since the Great Depression."
"You look at what's happening under Bush, and we've got a few people who are doing extremely well and everybody else is struggling," he told the group, which included farmers wearing bib overalls.
Edwards has been working to throw off the image of a wealthy politician with an extravagant home and expensive haircuts, and distinguish himself as a candidate for the working people. He frequently accuses his rivals, especially Clinton, of being Washington insiders out of touch with real people. At almost every stop he reminds crowds that his father was a mill worker, and that he put in his time at the mill before college.