听力原文： (21)An estimated eleven million or more people are living in the United States illegally. What to do about them is at the heart of the debate over immigration reform. Yet questions about legal immigrants also remain unanswered. For example, should the United States open its doors to more skilled workers? Many employers would like that. Or should Congress lower the current limits, to get employers to hire more American citizens.'? Or would that only lead them to move more jobs to other countries. What about a temporary worker program, as former President Bush proposed? Congress tried to pass an immigration reform. bill last year. But the Senate was unable to reach agreement. So, in place of legislative action, the administration announced new measures to increase border security and immigration enforcement. (22)The steps include more workplace raids to catch illegal immigrants and higher civil fines for their employers. According to this news, what is the main point of the debate over immigration reform?