If House Republicans get their way, President Obama won't be able to use any trade pact to strike a deal on climate change.

Late Tuesday evening, House Ways and Means Committee Chairman Paul Ryan of Wisconsin offered up an amendment to a customs bill that would "ensure that trade agreements do not require changes to U.S. law or obligate the United States with respect to global warming or climate change."

The customs bill is intended to amend so-called "fast-track" trade legislation that could see a House vote as early as this Friday. Fast-track would allow Congress an up-or-down vote on trade deals negotiated by the White House.

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The trade legislation sets out negotiating priorities that Congress expects the White House to abide by when striking international trade deals. House Republicans have promised to reject any deal that does not meet the objectives.

Environmentalists are up in arms over the provision, arguing that it sends the wrong message at a time when action to curb climate change is more necessary than ever to stave off the most devastating impacts of a warming Earth.

But Ryan, the former vice-presidential candidate, is working hard to win Republican support for the trade bill. Doug Andres, a spokesman for the House Committee on Ways and Means, said that the climate-change amendment acts as an olive branch for House Republicans fearful that the president might use his trade negotiating power to take action on climate change.

The measure to block climate deals in trade negotiations was added at the request of Rep. Jim Sensenbrenner, another Wisconsin Republican, a spokesman for the congressman confirmed. The New York Times first reported that Sensenbrenner asked for the amendment Wednesday evening. 

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"The language is just to ensure that the trade deal is not a vehicle to minimize congressional involvement in a future international agreement on climate change," Bart Forsyth, a spokesman for Rep. Sensenbrenner explained. 

Andres also noted that the provision was added in response to concerns raised by the congressional delegation from West Virginia, a coal-rich state heavily dependent on fossil-fuel extraction.

Rep. David McKinley of West Virginia has previously warned that the president could use fast-track to advance a radical environmental agenda.

"If given this fast-track authority, what could President Obama include in a trade agreement? He could mandate a reduction in the use of natural gas and coal at home and abroad, implement his controversial climate-change agenda, and impose radical environmentalist regulations," McKinley wrote in an op-ed in a West Virginia newspaper in February.

Greg Dolan, a spokesman for Rep. David McKinley, said the congressman did not ask for the amendment. A spokesman for Rep. Alex Mooney similarly said that the congressman did not request the amendment. A spokesman for Rep. Evan Jenkins did not return a request for comment.

Environmentalists—many of whom oppose the trade deal to begin with—quickly attempted to mobilize a counterpunch. The Sierra Club and the Natural Resources Defense Council sent a joint letter to House members Wednesday flagging the amendment and urging a "no" vote on the customs bill and fast-track.

"We need global trade deals to do their part in the fight against climate change by eliminating fossil-fuel subsidies, and this new language would prevent that entirely," said Karthik Ganapathy, a spokesman for the grassroots environmental group 350.org, adding that the provision might sink the effort to pass the trade bill by eroding Democratic support.

Progressive Democrats, labor unions, and environmentalists strongly oppose fast-track, warning that the sweeping international deals the president is working to negotiate could erode key environmental and labor safeguards, and even worsen climate change.

Obama, however, sees the completion of the trade deals as critical to his economic legacy. The White House and the U.S. trade representative have fought to cast the deals as beneficial to the environment, touting the fact that they have been negotiated to restrict illegal wildlife-trafficking and fishing.

The president wants to see Congress pass fast-track legislation to ensure that any trade deal would not be subject to a barrage of amendments in Congress. But the road to passage has not been smooth.

The White House would not comment on the amendment. The U.S. trade representative did not return multiple requests for comment. 

Fast-track also has met with fierce criticism from some House conservatives who say green-lighting the trade deal could give the president unchecked power.

When asked if the amendment had been added as a sweetener to lure hold-out Republicans to sign onto the trade bill, Rep. Tom Cole of Oklahoma, a supporter of the trade push and a member of the whip team, said he was not familiar with the amendment but noted it would make sense for that to be the intent.

"Yes, certainly there are fears right now that this could be used to give Obama unilateral authority. So we're working right now to ease those fears," Cole said.

This story has been updated with additional information.

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