This Week -- ABC News -- May 6Stephanapoulos: Is the issue central enough to really be the force behind a presidential campaign. Tancredo: I don't know. How can I say for sure? All I can tell you is how strongly I feel about it. I happen to believe it is one of the most important domestic policy issues we can deal with. It touches so many parts of our lives. If you want to talk about education, we certainly can - the impact of illegal immigration on our schools. If we want to talk about health care we certainly can - and the impact of illegal immigration on our medical system. Eighty-six hospitals closing in Southern California in the last few years because of the impact of illegal immigration... Watch