The two contenders appeared Saturday at the Democratic Party of Wisconsin's Founders Day Gala. CNN reported Clinton delivered a mild speech while Obama lashed out at Clinton.
He said Clinton, the junior senator from New York, "just recently" began supporting legislation aimed at keeping American jobs at home that he said he has long supported.
Obama, the junior senator from Illinois, said the Patriot Employer Act "will reward companies that create good jobs right here in America."
He also hammered Clinton for tailoring her positions because she is running for the White House, CNN reported.
"I didn't just start criticizing unfair trade deals like NAFTA and China because I started running for president," Obama said, referring to the North American Free Trade Agreement championed by Clinton's husband's administration.
NAFTA was signed into law by former President Bill Clinton.