I'm shamelessly copying this from Greg Mankiw's site. Economic liberty has too few quotable/charismatic defenders (but that could just as well be that it's not deemed interesting enough to make the news). What we do hear is the protectionists like Lou Dobbs and it's easier for a politician to cave into empathy for low paying jobs, doing what they think feels right, instead of doing what they likely know is right.
Anyway, here's US Treasury Secretary Paulson:
trade helps Americans provide for their families. When special interests seek protection in the name of low-wage workers, we should acknowledge that limitations on imports do not benefit the vast majority of Americans. They deny people the freedom to choose from a broader array of goods and services, and impose a cruel tax on people who rely on low prices to stretch their family budgets. The cost of protectionism falls most heavily on those who are least able to afford it – the poor and the elderly.