Senate Democrats on Tuesday delivered a stinging blow to President Obama’s trade agenda by voting to prevent the chamber from picking up fast-track legislation. 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...