U.S. Republicans make repealing Obamacare 'first order of business'

By Susan Cornwell and Richard Cowan WASHINGTON (Reuters) - President Barack Obama exhorted fellow Democrats on Wednesday to preserve his legacy-defining healthcare law as Republicans moved ahead with their long-sought bid to scrap it in what Vice President-elect Mike Pence called the "first order of business" of Donald Trump's administration. The emerging Democratic strategy is to warn that Republicans risk throwing the entire U.S. healthcare system into chaos by moving to dismantle the 2010 Aff