In the threadbare border towns of South Texas, one of the country’s poorest regions, enterprising locals like Candelaria Espinoza have long been paid to round up votes for candidates on Election Day. There is even a name for these electoral soldiers of fortune: politiqueras. So when Senator Hillary Rodham Clinton’s presidential campaign arrived in South Texas in February seeking an edge in its uphill battle against Senator Barack Obama, Ms. Espinoza was happy to oblige, for a price. The campaign paid her and seven other members of her family $100 to $200 each to knock on doors, deliver fliers and...
