As Congress prepares for a showdown over immigration policy, President Bush urged lawmakers Thursday to have a "civil debate" that respects people of all backgrounds. "Ours is a nation of law and ours is a nation of immigrants, and we believe that we can have rational, important immigration policy that's based upon law and reflects our deep desire to be a compassionate and decent nation," Bush said. He urged a serious debate on the issues at a time when advocates on both sides have been playing to voters' gut emotions. "When we discuss this debate, it must be done in...