"In terms of U.S. politics, the passage of NAFTA signaled that the Democratic Party—the “progressive” side of the U.S. two-party system—had accepted the reactionary economic ideology of Ronald Reagan

A “North American Accord” was first proposed by the Republican Reagan in 1979, a year before he was elected president. A decade later, his Republican successor, George H.W. Bush negotiated the final agreement with Mexico and Canada.

But the Democrats who controlled the Congress would not approve the agreement. And when Democrat Bill Clinton was elected in 1992, it was widely assumed that the political pendulum would swing back from the right, and that therefore NAFTA would never pass. But Clinton surrounded himself with economic advisers from Wall Street, and in his first year pushed the approval of NAFTA through the Congress."

http://www.epi.org/blog/naftas-impact-workers/

That's why I don't blame the advance of U.S. imperialism solely on the neocons and republicans. It's a duopoly that works hand in hand on the overall ruling class agenda. Obama clearly did the same thing Clinton did. And we can expect the same from Hillary Clinton. Sanders is a wild card, but like with Obama, we'd see within the first 100 days with his appointments whether he was real or he was Memorex.