Paul Ryan, the Republican congressman and former vice-presidential candidate best known for his war on spending, is emerging as his party's leading champion of immigration reform in the U.S. House of Representatives. With Senate passage of a sweeping immigration bill imminent, Ryan has been meeting with House conservatives to persuade them that reform of the immigration system, including a path to citizenship for illegal immigrants, is an economic necessity and critical to fixing the nation's fiscal problems. Ryan, a potential 2016 presidential contender, sees himself as a "bridge builder" between immigration advocacy groups and reluctant Republicans, he said in an...