This article is from the archive of our partner National Journal

Key Democratic groups are threatening to turn Capitol Hill trade policy battles into campaign fights—a rare situation for a party that has largely avoided the ideological litmus tests that have plagued Republicans.

In recent weeks, liberal groups have threatened a primary challenge to a top Democratic senator, and one of the party's biggest labor allies has cut off campaign funds to wage a fight on trade policy. "We're saying we're not going to stand for this," said the AFL-CIO's Celeste Drake. Her organization has put a freeze on its campaign donations to put Democrats on notice to oppose trade-promotion authority—which would set parameters on a trade deal negotiated by the Obama administration but limit congressional input on the deal to an up-or-down vote.

The AFL-CIO gave nearly $9 million to Democratic candidates last cycle, one of the highest totals among labor groups. Organized labor as a whole spent nearly $136 million on the 2014 elections, according to the Center for Responsive Politics, almost all of it to elect Democrats. Other big spenders, such as the National Education Association and AFSCME, have also come out against TPA.

Meanwhile, several progressive groups are openly talking of lining up a primary challenger to Sen. Ron Wyden, the top Finance Committee Democrat and a key player in the ongoing TPA discussions. "Wyden is in a position where he can decide whether or not there is a bipartisan fig leaf on fast-track authorization," said Democracy for America's Neil Sroka. "It would be a lot harder to talk about a primary threat if there weren't such opposition to [TPA]. "¦ We're making clear that there will be consequences."

(RELATED: Are Progressives Willing to Attack One of Their Own on Free Trade?)

Wyden's office did not respond to a request for comment. But whether it's progressive muscle-flexing or a desperate attempt to avert bad policy, Democratic trade supporters aren't happy with such threats. "Practically speaking, all that is going to do is kneecap the Democratic Party in advance of 2016," said a senior aide to pro-trade congressional Democrats. "The real effect here is just going to be hurting the party as a whole."

The Obama administration—with the support of most Republicans—is pushing for TPA, also known as fast-track, in advance of the long-in-the-making Trans-Pacific Partnership. The TPP includes a dozen countries and 40 percent of the world's GDP. The White House argues that the deal will be the most progressive of its kind, with strict labor and environmental provisions—but only if Congress gives Obama the leverage he needs by passing fast-track. Liberals counter that details on the agreement have been scarce, and that ceding their authority to alter the deal won't ease those concerns.

With or without Wyden's support, most observers expect TPA to pass the Senate—but the outcome in the House is still an open question. "The most obvious place that there's a real opportunity to stop this is in the House," Drake said, but acknowledged: "We are in the uphill battle position."

Most Republicans support TPA on principle but have also balked at expanding Obama's authority in many instances. And Speaker John Boehner's struggles to earn consensus in his caucus have been well documented. "He's going to need to get votes from Democrats—there's no doubt about it," said Third Way's Jim Kessler, who supports the deal. "Some Democrats are starting to listen "¦ but there's a substantial amount that are just going to reflexively oppose it."

(RELATED: "Fast Track" Can Happen. But Will Wyden Go Along?)

The pro-trade aide said the number of House Democrats who will support the deal could range from 10 to 45, but the aide added that Republicans are likely to have the votes regardless. "The real question is going to be how much Boehner can keep his troops together on this, and I suspect he's going to do a fairly decent job on this issue," he said.

As the question of passage lingers, so too do the threats from those who oppose it. And some suggest the fight's implications won't be limited to this spring's trade discussions. "Success in the fight against the TPP will show the strength of the progressive movement going into 2016," Sroka said. "We have no doubt that where you stand on these trade deals is going to be an important question that all presidential candidates are going to be asked."

Supporters of the deal see the ongoing battle less favorably. "My suspicion is that those who are of the anti-trade community would like to make this the first shot in a larger fight," said the pro-trade aide, singling out labor groups. "You have red-state governors who are trying to eliminate the very right to organize "¦ and they've chosen instead to attack the one party that is standing between them and oblivion."

Regardless of whether Obama's trade agenda goes through—or liberals pull the party's 2016 agenda to the left—there's little indication the primary threats have gotten much traction. Rep. Peter DeFazio, the groups' preferred challenger to Wyden, has said he's not running, although Sroka noted people have been known to change their minds. Still, he drew distinctions with the damaging ideological battles that have hurt GOP candidates in the past. "The difference between us threatening a primary and Republicans threatening a primary—this isn't about us wanting to take Wyden down," he said. "This is a principled stance, and he needs to know that there may be repercussions on it."

National Democrats don't seem to be too worried about the progressive challenge to one of their incumbents. "We're confident that Ron Wyden will be reelected so he can continue fighting in the Senate for Oregon's middle class," Democratic Senatorial Campaign Committee spokesman Justin Barasky said in an email.

Serious challenges or not, Democrats on the other end of the trade debate see the threats as unproductive. "Instead of taking what I would consider to be a golden opportunity to work with a sympathetic administration, they're bashing something that they haven't even seen yet," said the pro-trade aide. "If this agreement is killed this year, do they really want to see a Republican Congress negotiating out a TPP with President Walker?"

Kessler added that bad trade deals in the past have made Democrats skeptical, but he argued that opponents should give their president a chance to make his case. "That NAFTA shadow hangs over this debate," he said. "We have a president who's progressive as any president we've had in decades, and there should be at least some benefit of the doubt given that he's going to negotiate a deal that's going to benefit working-class Americans."

Fast-track opponents, though, don't seem willing to budge. "It's tough for Democrats to stand up against their president," Drake said. "This is something that the administration wants, it wants badly, and it's pushing pretty hard. "¦ Sometimes you just have to disagree with your friends."

This article is from the archive of our partner National Journal.

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