Some of the biggest names in copper have found high-ranking political allies to support their efforts to get the wiring metal added to a list of minerals deemed critical to the US.

Senator Kyrsten Sinema, an Independent from Arizona, sent a letter with other lawmakers on Thursday urging Interior Secretary Deb Haaland to “revisit and reconsider the designation of copper as a critical mineral.”

Signers included other senators whose home states are hubs of copper production and manufacturing, including Mark Kelly of Arizona, Joe Manchin of West Virginia, Indiana’s Mike Braun, Raphael Warnock of Georgia and Mitt Romney of Utah.

“This should be a no-brainer,” Sinema said in an interview. “We have major gaps in both our ability to mine and process these minerals to ensure our energy security for the future, and the administration knows how important copper is to our domestic and national security.”

The letter warns of a “significant increase in the supply risk” of copper driven by economic and geopolitical events like the war in Ukraine.

“Given the enormous investment required, the time lag for new sources of supply, and projected demand, time is of the essence,” the letter said.

Separately, Representatives Brian Higgins, a Democrat of New York, and Robert Latta, a Republican of Ohio signed a February 2 letter also calling on Haaland to immediately reconsider adding copper as a critical mineral.

The push adds to lobbying by the Copper Development Association to urge the US government to consider copper critical, joining a list of 50 other minerals already identified as vital by the government. The association’s members include some of the biggest copper producers including Rio Tinto Group, BHP Group and Freeport-McMoRan, as well as fabricators such as Mueller Industries Inc.

The US critical minerals list is updated every three years and includes key battery metals needed for electric vehicle production such as nickel, lithium and zinc. The latest update, in 2022, did not include copper despite the lobbying efforts, though it did add nickel and zinc. The senators are calling on the White House to skip the usual three-year review and add copper to the list as soon as possible.

Some of the world’s largest miners and metals traders have warned that a massive shortfall will emerge for copper, holding back global growth and throwing international climate goals off course given their importance to electrifying economies.