US President Barack Obama on Monday said Karen Mills, his cabinet-level chief of the Small Business Administration, was leaving his government, and praised her role in helping revive the US economy. "I knew she had the skills and experience to help America's small businesses recover from the worst economic crisis in generations -- and that's exactly what she's done," Obama said in a statement. "Over the last four years, Karen has made it easier for small businesses to interact with the federal government by reducing paperwork and cutting through red tape.