By Timothy Gardner

WASHINGTON (Reuters) -The U.S. on Monday said it is seeking up to 3 million barrels of oil for the Strategic Petroleum Reserve for delivery through May next year, a purchase that would leave the government with little money to buy more until lawmakers approve more funds.

The solicitation for the oil which would be delivered to the SPR's Bryan Mound, Texas site from April through May 2025, is the latest step in bringing oil back to the reserve after its biggest sale ever in 2022 of 180 million barrels.

President Joe Biden had ordered that sale after gasoline prices spiked following Russia's full-scale invasion of Ukraine.

The Department of Energy has now bought back more than 55 million barrels at an average price of about $76 per barrel, nearly $20 lower than the $95 a barrel price it sold the oil for in 2022.

As part of efforts to replenish the SPR, the department also worked with lawmakers in late 2022 to cancel 140 million barrels in sales that had been congressionally mandated through 2027. Democratic and Republican lawmakers had voted for those sales to pay for government programs.

It is unclear exactly how much money the DOE has left in its fund to buy more oil. A department source said earlier in the month that there was about $150 million left, or about enough to buy about 2 million barrels.

But evidently there is slightly more. "The DOE will continue to purchase crude at a good price for taxpayers with available emergency revenues," a department spokesperson said on Monday.

The Biden administration, or the next one, will need to work with Congress to fill up the DOE's SPR purchasing fund.

"Imminent depletion of the SPR petroleum account puts the onus on Capitol Hill for further replenishment, but politicization of the SPR could make it hard for lawmakers to agree," said Kevin Book, a policy analyst at ClearView Energy Partners, a non-partisan research group. Book estimated that "theoretically" there would still be some money left if the latest solicitation was fulfilled but that it would not be much.

Working with lawmakers on the SPR could also involve cancelling future sales that Congress mandated years ago of about 100 million barrels of oil from 2026 through 2031.

Cancelling the sales instead of buying oil only to resell it again could reduce wear and tear on the SPR's underground caverns on the Texas and Louisiana coasts, where the oil is held.

(Reporting by Timothy Gardner and Kanishka Singh in Washington; Editing by Leslie Adler and Andrea Ricci)