Vestas Wind Systems A/S's threat to fire 1,600 workers in the U.S. undermines President Barack Obama's goal of creating green jobs and adds to pressure on Congress to extend a tax credit that the industry relies on. The world's biggest maker of wind turbines said yesterday it will probably reduce its staff beyond the 2,335 posts it's eliminating worldwide if the U.S. doesn't renew the so-called Production Tax Credit, which expires at the end of this year. "We will evaluate it during 2012 depending entirely on how the political situation evolves," Chief Executive Officer Ditlev Engel said in an interview in Copenhagen. U.S. jobs will be scrapped "for sure" without the credit, and a decision is due "no later than the fourth quarter," he said.