[cnn-photo-caption image= http://i2.cdn.turner.com/cnn/2009/POLITICS/02/17/buy.american/art.obama.walk.gi.jpg caption="Trade will be a major issue when President Obama visits Canada beginning Thursday."]
(CNN) - President Obama takes his first foreign trip Thursday, but domestic politics will loom large as he tackles the explosive issue of protectionism in a meeting with Canadian Prime Minister Stephen Harper, the leader of the United States' largest trade partner.
At issue is a controversial so-called "Buy American" provision requiring the use of U.S.-produced iron, steel, and other manufactured goods in public works projects funded by the $787 billion economic stimulus bill.
Several Democratic-leaning unions and domestic steel and iron producers favor the provision; a large number of business and trade organizations are opposed.
Administration officials altered the language in the final version of the stimulus bill to ensure that the provision will not trump existing trade agreements such as the North American Free Trade Agreement, known as NAFTA. Canadian companies will therefore still have the chance to sell products used in stimulus-funded projects.
Canadian government officials, however, are still concerned by what they perceive as rising protectionist sentiment in the United States that could potentially spark a trade war and, in their opinion, deepen the global economic crisis.