WASHINGTON (Reuters) – A coalition of 14 conservative groups urged U.S. lawmakers on Wednesday to support an amendment to the House of Representatives’ annual defense bill that would prevent the Pentagon from implementing climate-change and green energy policies meant to save taxpayers money and protect the planet.

In a letter to the lawmakers, the groups said many climate programs “are likely to undermine military readiness by diverting scarce resources.”

The programs in question were initiated by former President Barack Obama’s 2015 executive order requiring the military to meet green energy and greenhouse gas emissions targets. The conservative groups are trying to gather support for Republican Representative Warren Davidson’s amendment to the House version of the National Defense Authorization Act that would stop the military from implementing the policies.

The groups include the Competitive Enterprise Institute, a libertarian advocacy group; Americans for Prosperity, a group funded by the conservative Koch brothers; and Americans for Limited Government.

U.S. Defense Secretary Jim Mattis has long been supportive of programs that reduce troops’ petroleum dependence. In written testimony to a Senate panel after his confirmation hearing in January, Mattis said “climate change can be a driver of instability” and is “a challenge that requires a broader, whole-of-government response.”

The House bill includes language from Democratic Representative Jim Langevin that would require the Pentagon to report to Congress on military bases that are most vulnerable from rising seas and other effects of climate change. It is uncertain whether Davidson’s or Langevin’s measures would be in the final House bill.

The House is due to vote this week on its version of the defense bill and the Senate version will follow later this year.

Myron Ebell, the head of global warming and international environmental policy at the Competitive Enterprise Institute, who also led President Donald Trump’s transition team for the Environmental Protection Agency, said in an interview that the Defense Department “needs to concentrate on its core mission and not waste a lot of time with irrelevant distractions that gain them some political cover.”

When asked about Mattis’ position on climate, Ebell said he had heard generals say for years that climate change is a risk and “I’ve never listened to one who seemed to have the slightest clue as to what he was talking about.”

The Defense Department, the largest U.S. consumer of energy, is planning to forge ahead with a decade-long effort to convert operations to green energy.