LORAIN, Ohio — Barack Obama struck at rival Hillary Clinton's base of support among blue-collar workers yesterday, accusing her of trying to back away from past support of the North American Free Trade Agreement, which is deeply unpopular in this economically lagging industrial state.

Surrounded by workers at a gypsum wall board factory near Cleveland, Obama laid responsibility for NAFTA squarely with her husband's administration, which secured ratification of the treaty. And he quoted from past statements she made supportive of the agreement, including one from 2004.

"Ten years after NAFTA passed, Sen. Clinton said it was good for America," Obama said. "Well, I don't think NAFTA has been good for America — and I never have."

Clinton campaign spokesman Phil Singer countered by citing a 2000 speech in which she described the trade agreement as "flawed" and a 2004 speech Obama made to the Illinois Farm Bureau in which he said the United States "benefited enormously" from exports under NAFTA.

Clinton had denounced the Obama campaign a day earlier for circulating fliers that she said distorted her record on NAFTA. An Obama adviser said the campaign was determined to keep the controversy alive to focus attention on the Clinton administration's trade record.

"Hold on a second," Obama said later at a rally in Toledo. "The Clinton administration championed NAFTA, passed NAFTA, signed NAFTA."

Primaries March 4 in Ohio and Texas are shaping up as a make-or-break test of the Clinton campaign's viability and even her husband has said she must win both states. Polls show a statistical tie in Texas and a narrowing lead for Clinton in Ohio. Rhode Island and Vermont also are holding primaries March 4.

Meanwhile, Obama picked up an endorsement of sorts from Nation of Islam Minister Louis Farrakhan.

In his first major public address since a cancer crisis, Farrakhan said yesterday that Obama is the "hope of the entire world" that the U.S. will change for the better.

The 74-year-old Farrakhan, addressing an estimated crowd of 20,000 people at the annual Saviours' Day celebration in Chicago, never directly endorsed Obama but spent most of the speech praising the Illinois senator.

Also yesterday, Republican Party members in Puerto Rico awarded all 20 delegates at stake to Arizona Sen. John McCain, who has vowed to help resolve Washington's relationship with the U.S. territory.

The Chicago Tribune and Associated Press contributed to this report.