A motion to cut off a filibuster and proceed to the trade bill fell short of a 60-vote hurdle in the 52-45 vote. Sen. Tom Carper (Del.) was the only Democrat to back it.

Senate GOP Leader Mitch McConnell (R-Ky.) switched his vote from yes to no to reserve his ability to return to the measure at a later date.

Fast-track is a top legislative priority for the White House, but it has run into significant Senate opposition that has been led by Sen. Elizabeth Warren (D-Mass.). 
It faces even more opposition from Democrats in the House, and the surprise Senate failure will raise doubts about whether the legislation will make its way through Congress.