As the federal government hurtled toward a shutdown Tuesday, two labor unions representing federal workers sued the Trump administration over its threats to conduct mass layoffs while the government is closed. The unions allege in the lawsuit that the Office of Management and Budget and its director, Russell Vought, broke the law by directing federal agencies to prepare “reduction in force” plans for a potential shutdown. The lawsuit also names the Office of Personnel Management, along with its director, Scott Kupor, for issuing instructions that federal employees may work during the shutdown in order to carry out the mass layoffs....