Congress is poised to passed a bill to provide health insurance to millions of low-income children. The House Democratic leader, Representative Steny H. Hoyer of Maryland, said the bill was "very much like" legislation twice vetoed by President Bush in 2007. Legal authority for the program expires on March 31. Congressional Democrats said they had decided to add a major provision allowing states to restore health insurance benefits to legal immigrants under 21, a goal of Hispanic groups since those benefits were terminated in 1996.