INDIANAPOLIS - Barack Obama and Hillary Rodham Clinton tried mightily Sunday to convince Indiana and North Carolina voters that there are stark differences between them on Iran, gasoline tax freezes and other issues in the closing days before crucial Democratic presidential primaries in those states.

Clinton painted herself as the sensitive champion of the middle class and the candidate of experience, while Obama presented himself as a thoughtful agent of change, someone who would not be lured by what his camp derides as sound-bite solutions to complex issues.

The latest polls show Indiana as too close to call, while Obama has an advantage of 5 to 9 percentage points in North Carolina.

The candidates' most vivid clash Sunday involved a two-week-old Clinton comment about how she would react if Iran attacked Israel with nuclear weapons.

"We will attack Iran," she told ABC on April 22. "In the next 10 years, during which they might foolishly consider launching an attack on Israel, we would be able to totally obliterate them."

Obama, appearing Sunday on NBC's "Meet the Press," struck back with calm outrage. "It's not the language we need right now, and I think it's language reflective of George Bush," he said.

Clinton, who was appearing at an Indianapolis town hall meeting on ABC's "This Week," defended her stance.

"I'm asked a question about what I would do if Iran attacked our ally, a country that many of us have a great deal of, you know, connection with and feeling for, for all kinds of reasons," the New York senator said.

"And yes, we would have massive retaliation against Iran," Clinton added, though she said, "I don't think they will do that, but I sure want to make it abundantly clear to them that they would face a tremendous cost if they did such a thing."

It was unclear whether any of this will dramatically affect Tuesday's outcome. Ann Siegfried, 59, a retired teacher from Huntington, Ind., watched both shows Sunday.

"I never want to see us get into a war of any kind, and to say we'd 'obliterate' says to me, 'War at any cost,' " said Siegfried, who plans to vote for Obama but also likes Clinton.

But, she said, attitudes toward Iran are not a defining issue for her.

The talk show skirmish -- one that continued as the candidates moved around the state Sunday to campaign -- also involved gasoline taxes.

Clinton called her plan to suspend the federal gasoline tax of 18.4 cents a gallon strong evidence that she is plugged in to concerns of the average worker. Obama on Sunday dubbed the idea a "classic Washington gimmick" and "a strategy to get through the next election" that would barely be noticed by consumers.

Clinton spokesman Howard Wolfson called the dispute a "critical distinction" between the two candidates. Clinton, he said, is "someone who understands the pain that middle class and working class families are feeling. ... Sen. Obama [is] somebody who just doesn't seem to understand middle class families are hurting and they need relief."

Obama countered that what's needed is a change in how Washington deals with such crises.

"Let's invest in alternative fuels," he said, "raising fuel efficiency standards on cars, and let's get serious about reducing consumption of oil, which is the only way that over the long term we're going to reduce gas prices."

Clinton maintained that her plan is not the only part of her proposal to reduce this country's dependence on oil.

"I have long-term plans, too," she said.