California Rep. Joe Baca has long pushed legislation he said would "open the doors to the American Dream" for first-time home buyers in his largely Hispanic district. For many of them, those doors have slammed shut, quickly and painfully. Mortgage lenders flooded Mr. Baca's San Bernardino, Calif., district with loans that often didn't require down payments, solid credit ratings or documentation of employment. Now, many of the Hispanics who became homeowners find themselves mired in the national housing mess. Nearly 9,200 families in his district have lost their homes to foreclosure. Congressional districts with large Hispanic populations often feature heavy...