The Senate narrowly invoked cloture on fast-track trade legislation Tuesday morning, setting up a final vote Wednesday that will surely send the bill to President Obama’s desk for his signature.

In so doing, Congress will surrender remarkable authority to Obama and his successors. For the next six years, Congress will be unable to amend any trade deal signed by the president, and only 50 votes will be required for Senate passage—a reduced burden that hasn’t been granted to minimum-wage hikes, equal-pay legislation, gun control, campaign-finance reform, nor any other non-budgetary legislation of the Obama era.

In exchange, these future administrations will promise to be guided by negotiating objectives in the fast-track legislation on human rights, labor standards, and the environment, though many experts and congressional Democrats have decried the objectives as meaningless—in some cases they are satisfied if the president self-certifies that unspecified “progress” was made towards the negotiating goal.

The Senate wasn’t supposed to have to vote again; it passed fast-track legislation weeks ago and sent it to the House. But House liberals rebelled and temporarily killed the House package by voting down a program that provides job training to workers screwed over by trade deals. This program was a Democratic priority, but one they strategically killed in order to hopefully stop the entire fast-track passage.

But House Speaker John Boehner held another vote last week and sent fast track back to the Senate without the trade-assistance program, and so the Senate had to vote again on this bill.

There was substantial doubt that Senate Democrats would back fast track without trade assistance for workers, but they did—resting on assurances from congressional Republicans that they will pass the assistance program soon.

The final vote was 60-37, achieving cloture by the thinnest possible margin. (Three senators were absent; Tennessee Republican Bob Corker was delayed getting to Washington, but said he would have voted for fast track; Senators Robert Menendez and Mike Lee both voted “no” last time.)

After the vote, Senator Sherrod Brown took the Senate floor and declared, “This is a day of celebration in the corporate suites of this country, to be sure.”

Senator and presidential candidate Bernie Sanders added that “this trade agreement was supported by virtually every major corporation in this country, the vast majority of whom have outsourced millions of jobs to low-wage countries all over the world.”

Thirteen Senate Democrats helped get fast track over the line: Michael Bennet of Colorado, Maria Cantwell and Patty Murray of Washington, Tom Carper and Chris Coons of Delaware, Dianne Feinstein of California, Heidi Heitkamp of North Dakota, Tim Kaine and Mark Warner of Virginia, Claire McCaskill of Missouri, Bill Nelson of Florida, Ron Wyden of Oregon, and Jeanne Shaheen of New Hampshire.

Right off the bat, some progressive activists pledged to exact a price for supporting fast track. “The Senate Democrats who allowed Fast Track should know that this vote will be remembered, it will not be erased, and we will hold you accountable,” said Jim Dean of Democracy for America in a statement. “Accountability could mean primaries now or in the future, taking no action in your next difficult election, or support for progressive alternatives in future Senate leadership elections. Make no mistake, the memory of this clear betrayal of working families will follow you for years to come.”

The threat about Senate leadership elections is particularly notable; Senator Patty Murray is reportedly seeking the whip post in the new Senate, and provided a crucial vote for fast track. The current whip and her presumed competitor for the post, Senator Dick Durbin, voted against fast track.

Once fast track passes tomorrow (there is only a 50-vote requirement post-cloture, which this bill will easily achieve) and Obama signs fast track, the fight turns to the highly controversial Trans-Pacific Partnership.

Sometime in the late summer or early fall, the Obama administration will finally release the full TPP text, after the president signs it. After 90 days, Congress can vote on it.

Without question, fast track makes the TPP much more likely to pass. No amendments can gum up the process or chase off support, and we already can easily see there are 50 votes in the Senate based on the fast-track votes. But the House remains no sure thing for the TPP. Fast track twice passed by only two votes.

When the TPP actually comes out, there will be some really ugly details that are likely to enrage liberals and solidify opposition among Democrats. For months the White House has been dodging some criticisms of the TPP by stressing that the text isn’t final, but that will no longer be an option.

The unknown details of the TPP, incidentally, are what Hillary Clinton cites for not yet having an official position on the trade deal. If the Democrat base gets truly riled up when the details do come out, she may end up opposing the deal. This would give cover for every congressional Democrat to do the same.

Members of the House will also be in the thick of their reelection campaign this fall, and increased progressive activism and actual primary challengers will no doubt make a TPP vote even harder.

On the Republican side, Boehner will almost surely have a more difficult time gathering Republican votes for the TPP than he did for fast track. One argument frequently made by Republicans during the congressional fast-track debate was that it benefited the GOP, too—that it was also a vote to give a theoretical Republican president in 2017 immense power to shape trade deals without congressional meddling. That has no application to the TPP debate.

And 2016 will no doubt have the same effect on the Republican side, as incumbents face challenges from opponents to their right who may decide to blast them for supporting Obama’s trade agenda. The presidential race provides more pressure, and we’re already seeing it: Only weeks ago, Ted Cruz voted to move fast track. Tuesday, he released an op-ed on bashing “Obamatrade” and voted against cloture.

So while progressives lost the fast-track battle, the trade debate isn’t quite over yet. “What [today’s vote] doesn’t mean is that Congress must pass [the TPP],” said Robert Weissman, president of Public Citizen. “When the inexcusable and anti-democratic veil of secrecy surrounding the TPP is finally lifted, and the American people see what is actually in the agreement, they are going to force their representatives in Washington to vote that deal down.”