WASHINGTON - The Senate's immigration proposal would cost $49 billion over the next five years and $127 billion over the next decade, according to the Congressional Budget Office. The majority of the costs would be for increased enforcement, such as hiring more Border Patrol officers and building more detention facilities. The legislation would offer a chance at citizenship for millions of immigrants. Spending on government benefits programs, including refundable tax credits for the working poor, would rise by $16 billion for the years 2007-11, and by $48 billion over the decade, the CBO said in a report released over the...