But with most Democrats now demanding that all four trade bills — fast-track, TAA, a customs enforcement bill and a package of trade preferences for African countries — move in a single package, Senate Majority Leader Mitch McConnell (R-Ky.) will have trouble rounding up enough votes. 

It’s unclear if the White House and GOP leaders can get the necessary 60 votes to advance the legislation. Senate aides on both sides of the debate anticipate a close vote.

Florida Sen. Bill Nelson, one of seven Democrats to vote for fast-track in the Finance Committee last month, said Monday afternoon he would not vote to end debate on the motion to proceed to trade legislation unless all four bills are combined.

He said the Democratic caucus is unified on the question, kicking the ball back into McConnell’s court.

Hatch and other Republicans do not want to tie the customs enforcement bill to fast-track because it includes controversial language penalizing trading partners that engage in currency manipulation.