Froman traces his friendship with President Obama to their days on the Harvard Law Review. That pedigree helped the trade ambassador win the argument within the White House for chasing the 12-nation Trans-Pacific Partnership, the largest regional trade pact in history. Capitol Hill has proved a tougher sell, but Froman’s pitch job helped overcome Democratic resistance last year and kept the package inching forward. Now populist crosswinds from the presidential campaign threaten the deal anew. Froman may need a buzzer beater, in the post-election lame-duck session, to salvage his world-bending project.