The giant pyramid of boxes rose behind the podium on Capitol Hill, meant to represent the signatures of two million Americans who were petitioning members of Congress to vote against the Trans-Pacific Partnership. Then a gust of wind blew the empty boxes over. “Like the TPP, it fell down like a ton of bricks!” joked one staffer as he rushed over to reassemble the prop.  

As the House approaches a critical vote on fast-tracking the trade deal, anti-TPP activists are trying their hardest to play up their numbers. “Our ranks continue to grow stronger and stronger, and with every week, more and more members are declaring against fast-track,” Representative Rosa DeLauro of Connecticut said at a June 3 press conference, rattling off a long list of advocacy groups fighting the trade deal. “We’re seeing here a tremendous upheaval in public opinion, because the public realizes that it’s time to fight,” Representative Alan Grayson added.

That’s certainly been true among the left’s most dedicated activists—a broad coalition of groups that have assailed the trade deal as a godsend for greedy corporations that hurts ordinary workers. Their vocal opposition has made it tough for President Barack Obama to find the votes he needs to fast-track the trade deal, which would lower tariffs and implement new investment rules between twelve nations. The current bill would grant the president the authority to finalize the trade agreement, which would then come to an up or down vote in Congress. Republicans have been more inclined to support the president than his own party, which put up a fight before the bill passed the Senate. The White House still needs to convince more wavering House Democrats to break with the majority of their colleagues and support fast-track. 

Democratic supporters of the deal argue that the opposition, though vocal, represents a minority view. “There is fairly broad support for what the president is doing among the public and Democrats. There is less support among the activist class of the Democratic Party, which is far more against it,” said Simon Rosenberg, a Democratic strategist who supports the TPP.

Recent polling suggests that ordinary Americans have generally positive feelings about free trade in the abstract, and that Democrats are in fact even more inclined to support trade than Republicans. A Pew poll from May showed that 58 percent of Democrats believe that free trade agreements have been good for the country, along with 53 percent of Republicans. A recent Gallup poll showed similar results, with 61 percent of Democrats viewing foreign trade an opportunity for economic growth through increased U.S. exports, rather than a threat from foreign imports; 51 percent of Republicans felt similarly. Overall, the public view of free trade agreements has grown more positive in recent years. And most know very little about the TPP itself. In a new New York Times/CBS poll, 78 percent of respondents said they knew “not much” or “nothing at all” about the Trans-Pacific Partnership, while only 6 percent said they knew “a lot.”  

But the opposition to the deal has been far more organized from the start. “The activists got out very early to define the terms of this before the administration did,” said Rosenberg. The AFL-CIO and its allies have organized more than 615 events since March to oppose the deal; they’ve held more than 50 in the past week alone, including a mock funeral marking the death of “middle class jobs” in one House Republican’s district and protests in many others. By contrast, Republicans have taken shots at the business groups for getting upstaged by labor unions on the issue; the GOP is also working to persuade conservative members who are pro-trade but fear granting more authority to Obama. 

Opponents to the trade deal point out that public opinion turns significantly more negative when people are asked about the specific impact of such agreements on jobs, wages, and the economy—the thrust of their vocal argument against the deal. In the Pew poll, 51 percent of Republicans and 44 percent of Democrats believe that free trade agreements lead to job losses, and similar numbers believe they depress wages. When asked whether trade restrictions are necessary to protect domestic industries, or whether free trade should be allowed “even if domestic industries are hurt by foreign competition,” two-thirds agreed with the latter, according to the new NYT/CBS poll. Said DeLauro: “Yes, we’re for trade. We are for trade. But not for trade agreements that put American workers at a disadvantage. And when you describe that, and you listen to what the concerns are of people, then they change their minds as to what is in their benefit. So you have to go beyond the first question that is asked.”

The TPP’s supporters have tried to assuage such concerns by playing up the job-creating potential of higher exports; that’s what has prompted the Democratic-dominated U.S. Conference of Mayors to support the agreement. Many policy experts believe that both the purported harms and gains from the TPP are being overstated in a heated debate. “There are going to be very few jobs that will be affected,” the Economic Policy Institute’s Robert Scott, who opposes the deal, told my former colleague Danny Vinik. Even legislators from the most export-driven districts remain unconvinced on the deal. According to a new Wall Street Journal analysis, “in the 10 districts with the biggest export growth since 2006, only three of the representatives” are currently backing the TPP.

But it’s not only been a fight about jobs, as the trade agreement’s parameters go well beyond the traditional purview of tariffs and quotas, spanning copyright protection, drug patents, and banking regulations. The TPP’s broad scope is one reason why there’s such a diverse coalition that's mobilized against it. At last week's press event, Representative Jan Schakowsky detailed her own concerns at length:

“I assure you that if you were to ask the American people, do you support a trade agreement that will allow private multinational corporations to challenge any one of the hard-fought-for consumer protections that we have, the cost of drugs, the clean food coming into this country, environmental regulations, to let these multinational corporations challenge these in a private extrajudicial tribunal that many of their lawyers could actually sit, and to say that they are going to lose profits, and that’s their reason for challenge our hard-fought-for consumer protections, I would guarantee you that there isn’t an American who would say they would support an agreement like that,” said the Illinois Democrat, referring to a major corporate dispute mechanism in the deal that has become a rallying cry for the opposition.

That's not a simple argument to communicate to ordinary Americans, especially as most haven’t been following the sprawling and complicated dispute very closely. “The problem we have is that most Americans do not understand the details of this,” Schakowsky admitted. Organizers admit that the issue won’t necessarily be at the forefront of swing voters’ minds. But they argue that it’s risky to disappoint the liberal activists who care deeply about the issue and whose participation will be critical to the 2016 elections. “A lot of Democratic members of Congress are in danger of losing their most dedicated supporters. It’s not just opponents flaring up, it’s opponents flaring up in their own backyard, and that’s a scary thing to be happening to someone facing re-election,” said Jason Stanford, a spokesman for the Coalition to Stop Fast Track. Labor organizers have already aggressively gone after one Democratic member, Representative Ami Bera of California, who’s received labor support in the past but is backing the agreement. 

Unlike their counterparts on the right, however, the left has generally been less willing to primary Democrats on ideological grounds. And the big intraparty fight over trade stands out in part because the Democratic Party has become so unified on the rest of its economic agenda. And Obama has used some of those other policy priorities to lure his party’s wavering members:  As Politico reported, he persuaded one Colorado Democrat to come on board by offering to work with him on infrastructure projects.