Republican lawmakers are calling on U.S. President Joe Biden’s administration to preserve documents related to the proposed sale of United States Steel to Japan-based Nippon Steel, expressing "serious concerns” that politics have tainted an ongoing national security review of the deal and raising the prospect of a congressional probe.

Four House Republicans wrote to Treasury Secretary Janet Yellen and Commerce Secretary Gina Raimondo on Friday, saying that recent developments related to the Committee on Foreign Investment in the United States (CFIUS) "have called into question the integrity of its decision-making process,” and demanding the preservation of records related to the steel transaction.

The matter raises "broader issues about whether the statutory mandate of CFIUS to prioritize national security considerations has been subordinated to political interests,” the lawmakers wrote, according to a copy of the letter obtained by Bloomberg News. The documents should "remain intact and available for any forthcoming oversight needs,” the letter, from some members of the House Financial Services Committee, adds.