Later this afternoon, the Senate will hold a procedural vote on Trade Promotion Authority (TPA) in an attempt to reach cloture and guarantee a floor vote on fast-track authority for Barack Obama on the Trans-Pacific Partnership (TPP) free-trade agreement. On its first go-around, TPA barely made it past this procedural hurdle, with only 13 Democrats coming along for the ride — and that package included Trade Adjustment Assistance (TAA), a key Democratic priority to buffer the effects of globalization for American workers. Without it, even those few Democrats may take a pass on TPA, which would once again put fast-track into park.

With the vote just hours away, Obama spent yesterday twisting arms, The Hill reports. He got Oregon’s Ron Wyden to commit to supporting the bill, but other former Ayes are holding out:

Backers of fast-track likely need 11 Democratic votes because five of the Senate’s Republicans voted against the trade package last month. Sens. Maria Cantwell (D-Wash.) and Heidi Heitkamp (D-N.D.) said Monday they are still reviewing their options, while Sen. Ben Cardin (D-Md.) insisted he wants fast-track to remain bundled with Trade Adjustment Assistance (TAA), an aid program for workers hurt by foreign competition. Democratic Sens. Chris Coons (Del.), Michael Bennet (Colo.), Jeanne Shaheen (N.H.) and Claire McCaskill (Mo.) declined to say Monday evening how they would vote.

Besides Wyden, Obama has four other former ayes in line to back TPA: Carper (DE), Nelson (FL), Feinstein (CA), and Kaine (VA), most of whose states will benefit from trade. Patty Murray (WA), a key figure in the earlier approval, has remained very quiet this week. If Murray drops her support over TAA, Obama’s down to one vote to swing the issue.

Treasury Secretary Jack Lew told CNN’s Fareed Zakaria Sunday that Obama has gone all in on lobbying for cloture, using some remarkable hyperbole to describe the effort:

But I think it will pass and the one thing I can say is the president has spared no effort on this. He has talked to more members than I can count, more senators than I can count. And everyone in the cabinet, including myself, is doing their job to try and get this across the finish line.

Er, there are only 100 Senators at any one time, and in this case only a dozen or so who matter. If that’s more Senators than the Treasury Secretary can count, that hardly builds confidence in our fiscal management, no? Obviously Lew’s using a figure of speech here, but it’s telling that Lew feels the need to hype Obama’s work with Capitol Hill to such an extent. His predecessors considered that kind of engagement par for the course, to use a term with which Obama should be rather familiar.

Obama could have more trouble than just with the Democrats. Republicans have come under considerable pressure from the base to put an end to “Obamatrade,” or at least not give Obama more executive authority to abuse than he already has. In the first cloture vote last month, four Republicans did not support it: Susan Collins (ME), Lee (UT), Paul (KY), Sessions (AL), and Shelby (AL), plus Enzi (WY) did not vote. Obama can’t afford to lose any other Republicans, but presidential hopeful Ted Cruz announced this morning at Breitbart that he’s backing out:

As a general matter, I agree (as did Ronald Reagan) that free trade is good for America; when we open up foreign markets, it helps American farmers, ranchers, and manufacturers. But TPA in this Congress has become enmeshed in corrupt Washington backroom deal-making, along with serious concerns that it would open up the potential for sweeping changes in our laws that trade agreements typically do not include. … Enough is enough. I cannot vote for TPA unless McConnell and Boehner both commit publicly to allow the Ex-Im Bank to expire—and stay expired. And, Congress must also pass the Cruz-Sessions amendments to TPA to ensure that no trade agreement can try to back-door changes to our immigration laws. Otherwise, I will have no choice but vote no. There’s too much corporate welfare, too much cronyism and corrupt dealmaking, by the Washington cartel. For too long, career politicians in both parties have supported government of the lobbyist, by the lobbyist, and for the lobbyist – at the expense of the taxpayers. It’s a time for truth. And a time to honor our commitments to the voters.

If Cruz bolts, that might put more pressure on Marco Rubio to reverse course, although free trade is important enough for Florida and for conservatives in general that he might stick with TPA. Unless Obama can convince one or more of the five Republicans who didn’t back cloture the last time to reverse their position, Obama may be looking at another defeat on trade.

Update: In the end, Obama, McConnell, and Boehner got their way. Cruz flipped to no but Mike Enzi cast an aye vote, and Obama only lost one of the Democrats who voted for TPA the first time around:

The outcome of this key procedural vote had been in doubt as a group of 14 pro-trade Democrats weighed whether to continue their support of the bill out of concern that a related workers’ assistance package might not pass both chambers. But after repeated assurances by GOP congressional leaders that workers’ assistance measure will be adopted, 13 out of 14 backed the bill. The vote was 60 to 37, passing by the slimmest margin needed to pass. A final Senate vote on fast-track could come as soon as later Tuesday, and it will then head to President Barack Obama’s desk for his signature.

McConnell says he intends to honor his pledge to those Democrats by bring the TAA bill to the floor next.