Key congressional Democrats are balking at a White House request for $1.5-billion in upcoming government funding legislation for a cache of enriched uranium, imperiling a top priority of the Biden administration aimed at weaning the US off of Russian imports of the fuel used in nuclear reactors.

The request is part of a broader plan to spend billions to create a US-based industry for uranium enrichment and other services needed to create reactor fuel through the purchase of the raw material from domestic producers. The issue has been a major focus for Energy Secretary Jennifer Granholm and others in the Biden administration who are concerned about the reliance on Russia, which overall supplies more than 50% of global enriched uranium.

But some key Democrats on both the House and Senate appropriations committee who are charged with doling out the funds have expressed concerns about the administration’s request, with some questioning the need for the money with no sanctions in place on Russian uranium imports, according to a person familiar with the matter. The person, who was granted anonymity to discuss non-public deliberations, cautioned the situation was fluid and no final decisions had been made.

“I’m concerned by the amount,” Senator Dianne Feinstein, a California Democrat who chairs the Senate Appropriations subcommittee with jurisdiction over the funding. “That’s an awful lot of money.”

The White House Office of Management and Budget declined to comment.

In their request, the Office of Management and Budget said it was needed for the creation of a “reliable fuel supply” for both the nation’s fleet of existing commercial reactors as well as a new breed of advanced reactors now under development.

The White House wants the funding as part of a must-pass bill needed to keep the US government open after September 30.

The appeal comes as the Biden administration continues to weigh slapping sanctions on Russia’s state-owned atomic energy company, Rosatom, in response to the Kremlin’s invasion of Ukraine. It’s also possible Russia could decide to halt exports of enriched uranium.

The Biden administration has described the US’s reliance on Russian imports of uranium “a vulnerability” for both national and economic security. The Energy Department has made the case that any interruption in the supply of enriched Russian uranium could cause operational disruptions at commercial nuclear reactors.

Russia accounted for 16.5% of the uranium imported into the US in 2020 and 23% of the enriched uranium needed to power US commercial nuclear reactors.

The US only has one remaining commercial enrichment facility, in New Mexico, which is owned by Urenco, a British, German and Dutch consortium. Bethesda, Maryland-based Centrus Energy is constructing an enrichment facility in Ohio.