On the eve of a crucial primary, John Edwards (search) declared "there are differences" with his Democratic rivals that he will underscore in a campaign that will stretch well into March.

Edwards collected the endorsement of the Milwaukee Journal Sentinel, the state's largest newspaper, and flew to appearances in four cities Monday as he sharpened his differences with rivals on trade issues important in the industrial Midwest, particularly the North American Free Trade Agreement (search).

"I was against NAFTA," said Edwards. "Governor Dean and Senator Kerry were for it. There are differences."

Polls have shown Kerry with a wide lead heading into Tuesday's Wisconsin primary, but Edwards vowed to press ahead regardless of his showing. While he has sought throughout the primary season to avoid attacking his rivals, Edwards said he would make differences clear and insisted there's plenty of time for voters to see those differences and make their pick.

"It's not too late because this primary process is going well into March," said Edwards. "I want voters to know what the differences are between us."

Edwards said charting out differences "on substance" was different than the sort of attacks some of his rivals have made, and did not break his pledge to wage a positive campaign.

The narrowing of the Democratic field has helped him make his case, Edwards said, because voters can now focus more clearly on the differences between the remaining candidates.

"Voters will get a better sense of who we are and what the differences are between us," the North Carolina senator said.

In making his case, Edwards was seeking to focus on trade in a state that has lost more than 74,000 industrial jobs since President Bush took office, and where trade is blamed for much of that loss. Critics see free trade agreements as encouraging American companies to ship jobs overseas, even as they put downward pressure on wages in this country.

Edwards was not in Congress when NAFTA (search) was approved, but said he opposed it when he ran for the Senate in 1998, and was using it as a key difference with both Kerry and Dean. He argues that his working-class background gives him a special understanding of issues like trade and jobs.

"The reality is we have to change what we're doing," said Edwards.

He opened his campaign day in a working-class neighborhood in South Milwaukee, and was spending the day at rallies in virtually every corner of the state as he sought to close the gap with Kerry. Meeting with reporters, Edwards said he would press forward after Wisconsin, even if he finished third.

Aides said Edwards had plans for a fund-raiser Wednesday night in New York, and was launching a three-day swing through five states which hold primaries on March 2, beginning Thursday. They insisted those plans wouldn't change regardless of the outcome of the Wisconsin primary.

Edwards said his working-class message was beginning to resonate with voters, giving him encouragement to continue. Aides said fund-raising was going well enough to allow Edwards to continue his campaign for the foreseeable future.

"You deserve a president who actually believes in you," said Edwards. "We don't believe in tearing people apart, we believe in bringing them together."

During his campaign for Wisconsin's primary, Edwards has stumped hard among workers who have lost jobs to foreign competition and sought to make the primary a referendum on free trade agreements, While his rivals have criticized the way the trade deals have been implemented, they voted for them at crucial times, Edwards argues.

"You and I can change it," said Edwards. "We can do something about it."