Just a week after formally launching her presidential campaign, Hillary Rodham Clinton is already being tested on a thorny issue for Democrats: free trade deals and their impact on workers.

The issue is a backdrop for almost any global economic affairs debate in Washington, with many Democrats and their backers arguing that free trade deals help big corporations, but drive American jobs abroad to cheaper labor markets.

On Thursday, the debate rose to a full boil when members of Congress from both parties announced legislation that would give President Barack Obama the "fast-track" trade negotiating authority he needs to complete a massive Asia-Pacific free trade deal.