US President Joe Biden on Thursday said he opposed plans to sell the company US Steel to a Japanese firm. He said it is "vital" that the business remain American.

Nippon Steel announced in December that it planned to buy US Steel for about 14 billion dollars. It said it wanted to "move forward together" and that the American company would retain its name, brand and headquarters in Pittsburgh, Pennsylvania. Nippon Steel also promised not to eliminate any jobs.

However, US Steel employees lined up to criticize the deal. Members of the United Steelworkers union said last year it would be an "understatement" to say they were "disappointed."

Biden released a statement on Thursday promising to have their backs and saying that he wanted the "iconic" company "domestically owned and operated."

Biden has courted union voters in his bid for reelection. He and his Republican rival, Donald Trump, know Pennsylvania can swing from one party to another. Trump has called the deal "horrible" and has said he would block it "instantaneously."