The U.S. and European Union together already account for nearly half of global GDP and a third of global trade flows, with some $2.7 billion worth of goods and services exchanged daily. The agreement would increase trade between the partners by $120 billion within five years, according to a study by the U.S. Chamber of Commerce. At the same time, it would add some $180 billion to U.S.-EU gross domestic product. Estimates put forth by the European Commission suggest a new trade pact could increase annual GDP by 0.5 percent in the EU and 0.4 percent in the U.S. by 2027.

Getting even those modest benefits may be tricky, though. Negotiators striving to reach a deal within an aggressive two-year time frame will have to sort through a host of different regulatory standards, particularly regarding food and agriculture.