WASHINGTON (AP) — Nippon Steel and U.S. Steel filed a federal lawsuit difficult the Biden administration’s decision to dam a proposed nearly $15 billion deal for Nippon to accumulate Pittsburgh-based U.S. Steel..

The suit, filed Monday within the U.S. Court of Appeals for the District of Columbia, alleges that it was a political decision and violated the businesses’ due process.

“From the outset of the method, each Nippon Steel and U. S. Steel have engaged in good faith with all parties to underscore how the Transaction will enhance, not threaten, United States national security, including by revitalizing communities that depend on American steel, bolstering the American steel supply chain, and strengthening America’s domestic steel industry against the threat from China,” the businesses said in a prepared statement Monday. “Nippon Steel is the one partner each willing and capable of make the obligatory investments.”

Nippon Steel had promised to take a position $2.7 billion in U.S. Steel’s aging blast furnace operations in Gary, Indiana, and Pennsylvania’s Mon Valley. It also vowed not to scale back production capability in the US over the subsequent decade without first getting U.S. government approval.

Biden on Friday decided to stop the Nippon takeover — after federal regulators deadlocked on whether to approve it — because “a powerful domestically owned and operated steel industry represents a vital national security priority. … Without domestic steel production and domestic steel employees, our nation is less strong and fewer secure,” he said in an announcement.

While administration officials have said the choice was unrelated to Japan’s relationship with the U.S. — that is the primary time a U.S. president has blocked a merger between a U.S. and Japanese firm.

Biden departs the White House in only just a few weeks.

The president’s decision to dam the deal comes after the Committee on Foreign Investment in the US, often called CFIUS, failed to succeed in consensus on the possible national security risks of the deal last month, and sent a long-awaited report on the merger to Biden. He had 15 days to succeed in a final decision.

In a separate lawsuit filed within the U.S. District Court for the Western District of Pennsylvania on the identical day, the businesses accused steel-making rival Cleveland-Cliffs Inc. and its CEO, Lourenco Goncalves, in coordination with David McCall, the pinnacle of the U.S. Steelworkers union, of “engaging in a coordinated series of anticompetitive and racketeering activities” to dam the deal.

In 2023 before U.S. Steel accepted the buyout offer from Nippon, Cleveland-Cliffs offered to purchase U.S. Steel for $7 billion. U.S. Steel turned down the offer and later accepted a virtually $15 billion all-cash offer from Nippon Steel, which is the deal that Biden nixed Friday.

The businesses allege that Goncalves, in collusion with the U.S. Steelworkers, maneuvered to forestall any party apart from Cleveland-Cliffs from acquiring U.S. Steel and to wreck the Pittsburgh manufacturer’s ability to compete.