WASHINGTON - President Bush challenged lawmakers on Friday to have the political courage to pass an immigration bill amid intense pressure from critics who call it amnesty and advocates who believe the current system is broken. Bush stressed that while voting for the bill might be politically risky, he does not think the measure itself is risky. "This is a difficult issue for a lot of folks," the president said. "I understand that. But because it's difficult probably means we need to work doubly hard to get it done. And now's the time to get it done. "No matter how...