Treasury prices rose Tuesday, erasing earlier losses, after weaker housing data raised concerns about the strength of the economic recovery, and as investors focused on negotiations in Washington over raising the debt ceiling. The National Association of Realtors said on Tuesday that U.S. existing-home sales dropped 1.0% last month to a seasonally adjusted annual rate of 4.94 million units, below the median forecast of a 5.1-million-unit rate in a