WASHINGTON (Reuters) – U.S. Senator Bernie Sanders and a group of Democratic lawmakers are pushing to raise taxes for companies that pay their chief executives at least 50 times more than their typical worker’s salary, saying the bill was needed to limit corporate greed. The union-backed proposal, which could impact some of the nation’s biggest companies and largest employers, would also require Treasury Department guidelines to prevent companies from avoiding the tax by using contractors rather than employees, the senators said in a statement on Monday. The bill could generate $150 billion in…