Democrat Hillary Rodham Clinton told union leaders and Iowa voters her economic leadership should be judged by how well the middle class fares — and that trade agreements should be rejudged to see if they're helping or not.

With the presidents of four unions that are supporting her in the audience, Clinton tried Monday to address one of her biggest problems with labor — her husband's signing of the North American Free Trade Agreement.

"I think it is time that we assess trade agreements every five years to make sure they're meeting their goals or to make adjustments if they are not," the New York senator said. "And we should start by doing that with NAFTA."

Her Democratic primary rival John Edwards has been criticizing her husband's role in NAFTA, particularly before union audiences that he is trying to win over and who feel it has cost U.S. jobs. Edwards wants to renegotiate the agreement that lowered economic barriers between the United States, Canada and Mexico.

But while Edwards and other Democrats have been increasing their criticism of Clinton, the leader in the race, she focused on President Bush during a two-day tour of Iowa aboard a bus emblazoned in red, white and blue with her name and "Middle Class Express."

Clinton's speech was full of nostalgia for the values she said she learned growing up in 1950s middle class America — and with negative statistics about the economy under Bush. She said there has been increasing globalization, a housing crisis, growing income disparity and fiscal irresponsibility, and Bush has failed to respond.

"Anybody who tells you the Republicans are the party of fiscal responsibility, just roll your eyes," Clinton said to laughter from an audience gathered at City Hall in Iowa's second largest city.

She said her father taught her about debt and the importance of a balanced budget, and she promised to take those values with her to the White House.

"I ask whether our middle class is expanding and getting ahead," she said. "Are we on the road to a more prosperous middle class or not? The administration has failed that test. My administration will not."

Republican National Committee spokesman Danny Diaz said although Clinton is talking about prosperity for the middle class, she would increase spending dramatically and raise taxes.

"Clinton's tax-and-spend express makes it clear once more that she truly believes the government knows best how to spend our money, run our health care, and raise our children," he said. "Luckily, the American people know better."