JOHNSTON, Iowa (CNN) -- Decorum dominated the final Democratic presidential debate in Iowa before the January 3 caucuses there, but contenders sought to distinguish themselves on questions of trade and economic growth.
The Democratic candidates face off Thursday in their final debate before the January 3 Iowa caucuses.
Sen. Hillary Clinton of New York harkened back to an era of "fiscal responsibility and economic growth" in the 1990s, during President Clinton's presidency. Yet she distanced herself from another of her husband's accomplishments, the North American Free Trade Agreement of 1993.
Clinton said she would seek to review and reform NAFTA if elected and focus on "smart pro-American growth."
The senator also sought to distinguish herself from Sen. Barack Obama of Illinois and former Sen. John Edwards of North Carolina.
"Everybody on this stage has an idea about how to get change," she said. "Some believe you get change by demanding it. Some believe you get it by hoping for it. I believe you get it by working hard for change. That's what I've done my entire life." Watch highlights and an analysis of the debate »
Obama also said he would review NAFTA, if elected, to address labor and environmental concerns.
Edwards said the United States should make concern about human rights a factor in trade agreements with other nations.
In addition to Clinton, Obama and Edwards, the debate included Sen. Joe Biden of Delaware, Sen. Chris Dodd of Connecticut and Gov. Bill Richardson of New Mexico.
The debate organizers, the Des Moines Register and Iowa Public Television, did not invite Rep. Dennis Kucinich of Ohio or former Sen. Mike Gravel of Alaska to participate, partly because their campaigns lack offices in Iowa.
One light moment in the debate came after the moderator asked Obama how he could talk of making a break from the past while seeking advice from advisers to former President Clinton. The question prompted laughter from Hillary Clinton.
"I want to hear that," she said.
The audience laughed. Obama paused.
"Hillary," he said. "I look forward to you advising me, as well." Watch Obama joke with Clinton »
The campaign trail this week tested the relationship between Clinton and Obama.
Clinton apologized to Obama Thursday after an adviser suggested that Obama's admission of past drug use could hurt him in a general election contest against the Republican nominee. The adviser who made that remark, Bill Shaheen, resigned Thursday as co-chairman of Clinton's New Hampshire campaign.
During the debate Thursday, Clinton, Edwards and Obama generally agreed they would seek an end to the war in Iraq, scrutinize executive orders issued by President Bush and reform the health-care system. They also pledged to wean the United States from a dependence on foreign oil.
"This is a moral imperative," Obama said.
Clinton envisioned a national effort toward a new energy policy similar in scale to the Apollo program of the 1960s, which sent manned missions to the moon.
"This has to call for a new form of American patriotism," she said.
Edwards continued his assault on "corporate power" and "corporate greed," saying he would end tax cuts on the wealthiest Americans and "take this country and democracy back."
Biden said he would do away with tax cuts on the wealthy, increase vehicle fuel efficiency and improve education.
Dodd referred to China as an adversary, as opposed to an economic competitor, and he called for taxing companies that pollute.
Richardson said the United States should consider economic sanctions on China, called for fuel-efficiency standards of 50 miles a gallon and said he worries that people are "losing sight of Iraq as the most important issue facing the country.
With just three weeks before the crucial Iowa caucus, the Democratic race is considered wide open.
Many political observers saw Clinton as the inevitable Democratic presidential nominee a few months ago, but Obama has steadily chipped away at her lead in recent months.
In a CNN/WMUR poll conducted by the University of New Hampshire and released Wednesday, Clinton and Obama are in a statistical dead heat in New Hampshire, which will hold the nation's first primary January 8. Clinton's 1-point lead over Obama, 31 percent to 30 percent, is within the poll's margin of error of 5 percentage points. Edwards came in third at 16 percent.
Recent polls also show the race tightening nationally. When the Democrats last debated in Las Vegas in November, Clinton led Obama 44 percent to 25, according to a CNN/Opinion Research poll. Now, the CNN/Opinion Research poll shows Clinton with a narrower lead nationally over Obama, 40 percent to 30 percent. E-mail to a friend