Seven weeks after the collapse of legislation in Congress, the outcry against illegal immigration is louder than ever, manifested by proposed clampdowns at the state and local level and an uproar over the arrest of an undocumented immigrant in the execution-style slayings of three New Jersey college students. Scores of organizations, ranging from mainstream to fringe groups, are marshaling forces in what former House Speaker Newt Gingrich calls "a war here at home" against illegal immigration, which he says is as important as America's conflicts being fought overseas in Iraq and Afghanistan. While most of the groups register legitimate, widespread...