Barack Obama insisted Wednesday that his support in Iowa is broadening and cast doubt on rival Hillary Clinton's ability to convince voters she can deliver the type of change he says his campaign represents.

With recent polling showing the Democratic presidential candidate catching up to the frontrunner in the early-voting state, Obama is pressing the case that he has the policy proposals and broad appeal to attract voters interested in change.

"There's no doubt that we represent the kind of change Senator Clinton can't deliver on. And part of it's generational," Obama told FOX News." Senator Clinton and others have been fighting some of the same fights since the '60s. It makes it very difficult for them to bring the country together to get things done. And I think that's what people hunger for."

That approach appears to be paying off. A Zogby poll of 502 likely voters taken Tuesday showed Obama with 25 percent support, three points behind Clinton. The margin of error was 4.5 percent.

By contrast, an American Research Group poll taken in Iowa between Oct. 26 and 29 of 600 likely voters put Clinton 10 points ahead of Obama, with 32 percent support. Clinton has lost footing in the polls ever since a debate last week in which she gave unclear answers on her position regarding a New York plan to give driver's licenses to illegal immigrants.

While Obama's campaign in Iowa kicked off with energetic support from younger voters, the Illinois senator said he now enjoys support from "all demographic groups."

"We have grassroots support. That's the reason we're statistically tied. We've got the best organization on the ground," Obama said. "You can have all the establishment you want and all the Washington endorsements you want, but ultimately people are going to make a choice on who really cares about them and who has a track record for fighting for them."

He added that voters are "tired of the tit for tat. They're tired of divisive politics. What they want is somebody who can unify the country, push back against the special interests and stand up for what they really believe in."

On a three-day swing through southeastern Iowa, Obama has highlighted plans to give tax cuts to the middle class, reduce health care costs and strengthen retirement security, part of his so-called "American Dream" agenda.

According to his plan, Obama would offset payroll taxes for average Americans and remove taxes on Social Security for retirees now making less than $50,000 a year. He wants to provide tax cuts up to $1,000 for working families, expand the Family and Medical Leave Act, create a fund to prevent foreclosures, reform bankruptcy laws and enroll workers in portable retirement accounts.

In an indirect reference to Clinton, Obama told an audience Wednesday that his approach to lifting up the middle class isn't based on politics as usual.

"This is what we must do to reclaim the American dream. We know it won't be easy. We'll hear from the can't-do, won't-do, won't-even-try crowd in Washington; the special interests and their lobbyists; the conventional thinking that says this country is just too divided to make progress. Well I'm not running for president to conform to this conventional thinking. I'm running to challenge it," he said.

Clinton's campaign called Obama's middle-class plan simply rehash of his earlier policy platforms and noted that Obama voted against capping credit card interest rates in 2005, a position upheld by congressional Republicans.

Fully aware of the gains Obama is making, Clinton just wrapped up a four-day swing in Iowa. She has also set out to hiring 100 new staff in Iowa and possibly doubling that army by election night on Jan. 3. Trying to widen the gap in Iowa, Clinton visited more than 30 cities this week to speak about her plan to increase biofuels production, achieve energy independence and create so-called "green" jobs.

On the generational shot taken at Clinton, her spokesman, Phil Singer told FOX News: "I think Iowa caucus-goers would disagree with the idea that anyone over the age of 50 should be disqualified from serving in elected office."

The studied Clinton response plays to the candidate's generational strengths as Clinton's supporter comes more consistently from older Iowans and a sizable number of baby boom women. These groups of voters tend to vote most predictably in caucuses and form the backbone of Clinton's pre-caucuses base.

Even so, the vast majority of the modest crowds who attended Obama events in Bettendorf and Muscatine were middle-aged and older and even divided between men and women.

David Axelrod, Obama's senior campaign adviser, said the Zogby data was consistent with internal campaign tracking polls. Axelrod said this was no time for victory laps.

"We've never jumped up and down about polls, but what those numbers show is what we see on the ground."

Axelrod said the Obama movement is not entirely driven by intense coverage of Clinton's up-and-down performance at last week's debate.

"We've been moving steadily," Axelrod said. "Now, obviously the debate opened up some questions about Clinton and that's a matter the candidates have followed up on."

Axelrod said the tightening of polls in New Hampshire underscores the campaign's ability to challenge Clinton on two fronts at the same time.

"We're not putting all our eggs in the Iowa basket, we've got the resources to go to February 5th and we intend to got that far and farther."

Axelrod said Obama will spend the majority of time between now and caucus night (Jan. 3) in Iowa.

"For us exposure equals success," Axelrod said. "People here fundamentally get what he has to offer."

FOX News' Major Garrett contributed to this report.