U2’s lead singer, Bono, is continuing his efforts to persuade the world’s wealthy industrialized nations to forgive Third World debt. The Irish rocker appeared with U.S. politicians and clergy members at a Washington, D.C., press conference on Thursday to ask the U.S. Congress to allocate $1 billion to eradicate debts that underdeveloped countries owe to the United States. “This is the time for America to show some heart,” Bono said, calling the monies owed by poor countries’ economic “slavery and debt bondage . . . It is immoral to have a farmer in Chad service debts to the richest countries in the world rather than feed his starving children.” Last month, Bono sang a duet with hip-hop singer Wyclef Jean at Net-Aid in New Jersey’s Meadowlands Stadium, one of the concerts held to raise money for the cause and draw attention to its Web site.