The House yesterday unanimously approved legislation that would provide $582 million to pay back dues to the United Nations — a reflection of how the political landscape has been altered by the attacks two weeks ago. For months conservatives have blocked the payment of the U.N. arrears. During a brief floor debate yesterday afternoon, followed by a voice vote, both Republicans and Democrats said the United States cannot afford to ignore the U.N.’s needs at a time when Bush administration officials are seeking a broad international coalition to support U.S. military strikes against Afghanistan. White House officials have lobbied behind the scenes for the money since the attacks.