Three U.S. senators — two Democratic presidential candidates and one of the party’s premier nuclear doves — urged House and Senate lawmakers negotiating the final version of the 2020 National Defense Authorization Act to tightly limit future U.S. production of plutonium nuclear-weapon cores.

That is according to a letter dated Sept. 13 and delivered to the leaders of the House and Senate Armed Services committees from Sens. Edward Markey (D-Mass.), Bernie Sanders (I-Vt.), and Elizabeth Warren (D-Mass.).

“We call on you to support the House language, which sensibly reduces the 80-pit requirement to 30 pits per year by 2026,” the lawmakers wrote in a three-page letter. “It also cuts funding for pit production by $241 million, to $471 million.”

The local Aiken, S.C., Standard newspaper first reported on the letter last week.

House and Senate Armed Services leaders, and members of their committees, are now negotiating a compromise version of the annual National Defense Authorization Act: a must-pass bill that sets budget limits and policy for U.S. defense programs, including the nuclear weapons programs managed by the Department of Energy’s National Nuclear Security Administration (NNSA).

Sanders and Warren are seeking the Democratic nomination to run for president in the 2020 general election. 

The NNSA plans a plutonium-pit production complex at DoE facilities in New Mexico and South Carolina, which by 2030 would annually manufacture 80 of the softball-sized nuclear-weapon cores. Initially, these pits would be for W87-1-style warheads, suitable for use on future Ground-Based Strategic Deterrent intercontinental ballistic missiles.

Internal NNSA studies show the agency is unlikely to hit the 80-pit throughput by that date. Charles Verdon, NNSA deputy administrator for defense programs, in April told Defense Daily that the agency has identified a solution to the issues raised in those studies. However, neither he nor other NNSA officials have publicly disclosed the details of this workaround.

Under the NNSA’s current plan, pit production would begin at upgraded facilities at the Los Alamos National Laboratory in 2024. The lab would produce 30 pits a year by 2030, while a new pit plant to be built at the Savannah River Site in Aiken, S.C., would come online in 2030, cranking out the additional 50 pits a year the NNSA needs by that year.

The Pentagon wants to start deploying GBSD missiles to replace aging Minuteman III missiles by 2030 or so.

Nuclear weapons have become a major defense issue for Democrats, who now control the House of Representatives and are seeking to oust President Trump (R) from the White House next year. Democratic policy has crystallized around slowing deployment of new intercontinental ballistic missiles, and prohibiting deployment of a new low-yield, submarine-launched ballistic missile warhead: the W76-2.