Republicans are trying to subvert their own government’s foreign policy on climate change. Next week, President Obama will fly to Paris for the U.N. Climate Change Conference, a meeting to work out a global agreement to reduce climate pollution. The Obama administration has put enormous effort and resources into building mutual trust between nations to get an agreement. In particular, the president has scored hard-won diplomatic victories by persuading some of the largest developing countries such as China and Brazil to make surprisingly strong offers of intended emission curbs. (They have been less successful with India, although more than one might have expected.)

The only remaining global outlier—the only major political party that denies climate science and opposes even the effort to reach a climate deal—is here in the U.S.: the Republican Party. And they’re doing everything they can to interfere with and undermine Obama’s efforts.

Last week, the GOP-controlled Senate voted 52-46 for two measures: one that would overturn the EPA’s Clean Power Plan, which will limit carbon pollution from power plants, and another that would revoke the EPA’s authority to regulate greenhouse gases under the Clean Air Act. The Clean Power Plan is the largest component of Obama’s Climate Action Plan, which would achieve the carbon emission cuts he is promising the global community. The votes were nearly party-line, with three just Republicans (Kelly Ayotte of New Hampshire, Susan Collins of Maine, and Mark Kirk of Illinois) and three Democrats (Joe Donnelly of Indiana, Heidi Heitkamp of North Dakota, and Joe Manchin of West Virginia) crossing the aisle. The GOP-controlled House has previously passed legislation to repeal the Clean Power Plan. Obama has promised a veto.

Overturning the Clean Power Plan would mean that the U.S. is less safe in promising that it will meet the emission targets it has pledged in the run-up to Paris: cutting greenhouse gas emissions 26–28 percent below 2005 levels by 2025. (Though it would still be possible to meet them if solar, wind, and natural gas continue to be substituted for coal for economic reasons.) If the U.S., the world’s biggest historical carbon polluter and second-biggest current-day polluter, is perceived as being unable to deliver on its climate promises, then other countries might not be willing to make promises of their own.

Republicans are trying to kill the Clean Power Plan in part to appease their conservative base and fossil fuel industry donors. But why now, less than two weeks before the climate negotiations begin? That’s not about sending a message to the folks back home, most of whom have never heard of the Clean Power Plan. It’s intended to influence negotiators from other countries.