Washington (CNN) Sen. Bernie Sanders compared his record with Joe Biden's on trade and foreign policy on Monday, attempting to draw sharp contrasts between himself and the former vice president as the two lead the Democratic presidential pack.

When asked by CNN's Anderson Cooper if Sanders was concerned about Biden's endorsement from the International Association of Fire Fighters, the Vermont independent said, "I'm running against, I think, 19 other people, so I'm concerned about everybody," with a laugh -- before setting out a brief history of their political disagreements.

"But I think when people take a look at my record versus Vice President Biden's record -- I helped lead the fight against (North American Free Trade Agreement); he voted for NAFTA," Sanders said on "Anderson Cooper 360."

"I helped lead the fight against (permanent normal trade relations) with China; he voted for it. I strongly opposed the Trans-Pacific Partnership; he supported it. I voted against the war in Iraq; he voted for it."

Sanders' comments offered a preview of the debates likely to dominate the Democratic primary, as the party's recent progressive push comes up against its more corporate-friendly, moderate establishment. Biden and Sanders, despite their differences on policy, both see electoral bases of support in the industrial Midwest and among organized labor. By underlining his opposition to trade deals mostly reviled by leading unions, Sanders, who has also criticized President Donald Trump's record on this front, could cut into Biden's support.

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