The position of most US presidential candidates on illegal immigration seems to be, "We don't want you here, but once you're in we'll help you out." Most of them, except for the far-left Denis Kucinich, voted for the security fence along the southern border, while Edwards, Obama, and McCain have supported bills to let illegal immigrants in-state tuition at state universities. Most candidates have also voted for President Bush's guest worker programme, which would allow current illegal immigrants to come out into the open, work seasonal jobs and then return home. But apart from this guest-worker programme, most of the policies supported by the candidates are the opposite of what America needs.
If we are to treat the labour market like any other market, workers should be able to cross borders just like any other good in a free trade system. Workers come to America to pick up jobs that the nation requires, like fruit picking, but have been priced out of the American labour market by the minimum wage. The construction of a fence or other measures to curtail this practice mean that the symbiotic relationship between American industries and illegal workers has begun to break down, with the possibility of harming the American economy more than most people realize.
However, this economic thinking is far from the mindset of most Americans, who fear the threat of illegal immigrants both in terms of national security and their own jobs. Granted, workers function a bit differently than goods like bananas or car parts, possibly demanding health care, education, and other social services. But the reactionary position of most Americans toward immigrants means our candidates support policies in line with similar thinking, no matter the economic story. In reality, their position should be, "we do want you here to take those jobs that we don't want, but we won't help you out if you choose to come and then can't support yourself." Assuming that the workers cross the border to gain better employment than they could at home, a policy like this would benefit all parties involved.