The Senate’s unanimous voice vote to weaken a controversial “Buy American” provision has sparked an outcry and reinvigorated a lobbying offensive by manufacturing groups that support the measure.

The new language ensures that the Buy American provision, which requires that stimulus-funded public works projects use American-made materials, will be consistent with U.S. international trade agreements.

The U.S. Business and Industry Council, which lobbies on behalf of nearly 2,000 small manufacturing companies, is responding to the watering down of Buy American with a lobbying effort to try to strengthen the language in conference.

“We don’t see how outsourcing-focused trade deals or how continuing to abide by outsourcing trade deals is going to help the nation grow its way out of this crisis,” said the council’s Alan Tonelson.

The group is activating its membership to contact Members of Congress and will be targeting like-minded lawmakers in order to ensure there is no more “backsliding” on the Buy American provision, according to its president, Kevin Kearns.

“There was no reason for the Dorgan provision to have this coda,” Kearns said, referring to Sen. Byron Dorgan (D-N.D.), the chief sponsor of the Buy American amendment.

The Senate version had required that only American-made equipment and goods be used in stimulus-funded projects.

The House stimulus package, which was approved last week, targeted foreign steel and iron, largely barring it from public works projects funded by the bill.

The Alliance for American Manufacturing, another supporter of Buy American, is also continuing to fight. The group, which blitzed Capitol Hill this week with grass-roots members visiting 70 Senate offices, is keeping a close on eye on the final product.

“We’re going to be continuing to fight off attempts to weaken it still,” said Scott Paul, executive director of the group. “That’s our first and primary goal.”