In recent months, progressives have been voicing their opposition to the Trans-Pacific Partnership. And they might try and make an example out of Sen. Ron Wyden over it, even though he's been a reliable ally for years.

The free trade agreement, which would involve 12 Asia-Pacific countries—including the U.S. along with countries like Mexico, Japan and Canada—could account for 40 percent of global GDP and one-third of all world trade. Progressive groups say that the deal is no good: it could ship more jobs overseas, undercut environmental and labor standards, and increase Internet censorship. The deal's future may rest with Wyden, the ranking Democrat on the Senate Finance Committee, and his support for the partnership has some progressives thinking about going after one of their own in their fight against the deal.

Wyden's support for the partnership has led the Oregon wing of the Working Families Party, a minor political party that supports progressive candidates and causes, to challenge Wyden in his next Senate race in 2016, the party's state director Karly Edwards told National Journal on Wednesday. The group takes issue with Wyden's support for trade promotion authority, also known as "fast track," which would allow the Obama administration to negotiate the Trans-Pacific Partnership with other nations without having Congress amend or filibuster. It's also not a fan of Wyden's previous support for the North American Free Trade Agreement and the Central American Free Trade Agreement.

"Wyden has a track record of supporting job-killing trade deals," Edwards said, adding that the party also opposed Wyden in 2010. "We have smart, savvy voters. They will take account the entire picture."

To illustrate the point of their frustration, progressive group Democracy for America commissioned a Public Policy Polling survey, which found in a leading poll last month that half of all Oregon voters would be less likely to vote for Wyden if he voted for trade promotion authority and the Trans-Pacific Partnership. It also showed that 63 percent of voters opposed the trade deal and 73 percent opposed trade promotion authority.

Whether the polling is an accurate measure of voter sentiment is not what matters here. What does is the message the poll sends to Wyden: that progressive groups would hold him accountable on the trade deal.

Wyden has generally been viewed as a strong advocate for progressive values on Wall Street and social issues. He opposed the 2008 bank bailout on the grounds that it rewarded bad behavior, and this week released a report showing how many high-income earners use various means to avoid paying taxes on capital gains. He was one of the first senators to support gay marriage, having backed it as a candidate in 1995.

Wyden also has been an advocate of progressive issues relating to technology, having long been a supporter of net neutrality. And he's a leading opponent of state secrecy surrounding the National Security Agency, which has earned him praise from civil libertarians.

But Neil Sroka, communications director for Democracy for America, said it was precisely because of Wyden's criticism of state secrecy on surveillance that his support for the Trans-Pacific Partnership is so glaring.

"I don't understand how you can be concerned about egregious concerns of secrecy in the NSA and the shirking of civil liberties and not be brutally concerned about the secrecy among these trade deals," Sroka said.

Fight for the Future, an internet activist organization that supports net neutrality, sent an email on Wednesday to supporters praising Wyden for his support for Internet freedom, but calling for him to back down on the trade deal, which the group says could lead to Internet censorship.

Wyden joins top Republicans—like his counterpart on the Finance Committee, Chairman Orrin Hatch, and Majority Leader Mitch McConnell—in his support for the trade deal. It's not the first time, or for the only issue, that Wyden has crossed the aisle. In the past, Wyden has consistently tried working on tax reform with Republicans, like Indiana Sen. Dan Coats and former New Hampshire Sen. Judd Gregg. In 2011, Wyden even teamed up with Wisconsin Rep. Paul Ryan on a Medicare reform plan that would allow recipients to keep traditional Medicare as an option or purchase Medicare-approved private plans.

Wyden said in a statement to National Journal on Thursday that he understands that middle-class families need assurances on trade deals that they feel don't work for them.

"That is why I am pushing hard for more transparency and oversight in trade negotiations, much stronger enforcement of the rules to hold trade cheats accountable, strong protections for labor human rights and the environment, and new rules that are fundamental to preserving free speech and the exchange of ideas over the Internet," he said.

Wyden could face opposition from other Democrats and groups aligned with Democrats in 2016. On Wednesday, Rep. Pete DeFazio, a Democrat from Oregon who challenged Wyden for the Senate nomination in 1995, criticized the Trans-Pacific Partnership in a press conference on Capitol Hill, saying it would be "the road to ruin for U.S. manufacturing and middle-class jobs."

Sroka said Democracy for America has previously floated the idea of DeFazio challenging Wyden but DeFazio's office said the congressman was surprised by suggestions that he would challenge Wyden, and said he was not interested in running for the Senate

At the same conference, the Oregon AFL-CIO President Tom Chamberlain criticized both the trade deal and trade promotion authority.

"It's time to put all the details out there, let democracy work and end a corporate-funded agenda that ignores the working people of Oregon, and of the United States," he said.

Correction: An earlier version of this story misstated the year Pete DaFazio challenged Ron Wyden for a Senate nomination. It was 1995.

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