US Steel and Nippon Steel have filed a lawsuit against Joe Biden’s order that blocked the $14.9 billion buyout of the American steel company by the Japanese company, they said on January 6.

According to The Guardian, the lawsuit asked the court to set aside the review process of the committee on foreign investment in the U.S., and Biden’s January 3 order, citing “violation of the constitutional guarantee of due process and statutory procedural requirements, as well as unlawful political influence.”

The case was filed in U.S. court of appeals for the District of Columbia circuit. The companies also filed a second lawsuit against rival bidder Cleveland-Cliffs, its CEO Lourenco Goncalves, and David McCall, the United Steel Workers union president, “for their illegal and coordinated actions” aimed at preventing the deal.

Political and union resistance to the deal had grown in recent months. Biden and Donald Trump, who is set to take office later this month, had opposed the deal, and the Biden administration told Nippon Steel in a letter in September that the deal would pose a national security risk by harming the U.S. steel industry.

US Steel has warned that a failure to conclude a deal would put thousands of U.S. union jobs at risk and had also signaled it would close some steel mills.