SPRINGFIELD, Ohio — Fighting back, Democratic Sen. John Kerry called President Bush "unfit to lead this nation" because of the war in Iraq and his record on jobs, health care and energy prices. He lashed out Thursday at Bush and Vice President Dick Cheney for avoiding service in the Vietnam War.

"I will not have my commitment to defend this country questioned by those who refused to serve when they could have and who misled America into Iraq," he said to a crowd of thousands at a midnight rally.

Cheney and Sen. Zell Miller, D-Ga., led a chorus of Republicans who challenged Kerry's credentials to be commander in chief, arguing that although they respect his decorated Vietnam War service, his 20-year voting record in the Senate on national security issues made him unfit for the nation's top job.

Kerry answered his critics with a blistering statement.

"For the past week, they attacked my patriotism and even my fitness to serve as commander in chief," Kerry said. "Here is my answer to them. I will not have my commitment to defend this country questioned by those who refused to serve when they could have and who misled America into Iraq."

Bush served stateside in the Texas Air National Guard. Cheney received five deferments and never served in the military.

Kerry also said that he and his running mate, North Carolina Sen. John Edwards, would be "hitting the road across America's heartland" describing their plans to move the nation in a new direction.

"We'll go out and talk with Americans in towns across Ohio, Iowa, Wisconsin, and Michigan. And because a stronger America begins at home, we'll talk about our plan to create jobs, cut taxes for the middle class, lower health-care costs, and make America safer and more secure."

Earlier Thursday, Edwards accused Republicans of using their convention to assail Kerry rather than offer ideas for solving the nation's most pressing problems.

The GOP spent "all of their time and all of their energy trying to tear down a patriot," Edwards told a town-hall audience in the Philadelphia suburb of Norristown, Pa.

"The anger we heard from Senator Miller, the anger we heard from the vice president — anger is not going to change this country and do what needs to be done for America," Edwards said. Where was the "anger and venom" about the millions of Americans who had lost their health insurance or their jobs? he asked.

"It doesn't surprise me that the vice president of the United States spent most of his speech talking about John Kerry because you know he doesn't want to talk about what they've done to this country," the North Carolina senator said.