Joshua Tree National Park began as a national monument created under the Antiquities Act. (timotale/iStockphoto)

Environmental groups are breathing a sigh of relief after the U.S. Senate defeated an attack on the president's ability to declare national monuments by executive order.



Lawmakers on Tuesday killed an amendment to the Senate energy bill that would have modified the Antiquities Act to make all presidential national-monument designations temporary for three years, and subject to approval by Congress and the relevant state legislature.



If ultimately passed, said David Myers, executive director of the Wildlands Conservancy, the change effectively would have blocked most new national monuments.



"I think it was a real vote for reason that the majority of the United States Senate believes in the value of our public lands, and the ability of the president to set aside these unblemished landscapes for perpetuity, when it's the only way to get it done," Myers said.



Conservation groups have urged President Obama to declare three national monuments in the Southern California desert: Mojave Trails, Sand to Snow and Castle Mountains.



Myers said a bill by Sen. Dianne Feinstein, D-Calif., to create the monuments has stalled.



"The senator tried for six years to get legislation passed," he said, "but it had no chance in passing through a Republican-led Congress."



The Antiquities Act has been used equally by Democrats and Republicans since its inception in 1906 under President Theodore Roosevelt. Grand Canyon, Joshua Tree and Grand Teton national parks all started out as national monuments declared under the Antiquities Act.



The amendment text is online at congress.gov.