“You know, in the years after her husband signed Nafta, Senator Clinton would go around talking about how great it was and how many benefits it would bring,” Mr. Obama said. “Now that she’s running for president, she says we need a time-out on trade. No one knows when this time-out will end. Maybe after the election.”

Mr. Obama, who has won 21 states in the Democratic presidential nominating fight, is working to add Wisconsin to his string of victories by tapping into an anti-war sentiment. As he pointed out his opposition to the war, he linked Mrs. Clinton with Senator McCain as he pointed out the failures of Washington.

“It’s a Washington where politicians like John McCain and Hillary Clinton voted for a war in Iraq that should’ve never been authorized and never been waged  a war that is costing us thousands of precious lives and billions of dollars a week,” Mr. Obama said.

In his speech in Janesville, Mr. Obama proposed creating a National Infrastructure Reinvestment Bank to invest $60 billion over 10 years and create nearly 2 million new jobs in the construction field. He said the program would be paid for by ending the Iraq war. He also renewed his call to create an energy plan to invest $150 billion over 10 years to establish a “green energy sector” to add up to 5 million jobs in the next two decades.

“It’s time to stop spending billions of dollars a week trying to put Iraq back together and start spending the money on putting America back together instead,” Mr. Obama said. He added, “We’ll also provide funding to help manufacturers convert to green technology and help workers learn the skills they need for these jobs.”

Mrs. Clinton, speaking before an enthusiastic crowd on Wednesday morning in McAllen, Texas, also struck economic themes, saying she offered solutions for voters’ financial struggles while Mr. Obama offered “rhetoric.”

The New York Democrat blasted her Democratic rival for the nomination for having “a plan that fails to provide universal health care, fails to address the housing crisis, and fails to immediately start creating good-paying jobs.”