The CEO of US Steel has warned of plant closures if the planned sale of his company to Nippon Steel falls through.

David Burritt made the remarks to the Wall Street Journal.

Burritt said a failed deal would cause workers to lose their jobs and the company's headquarters to move from Pittsburgh, Pennsylvania, to the southern US. He added that investment from Nippon Steel is critical to remaining competitive, as US Steel "doesn't have the money."

The United Steelworkers union, however, says the threat of closures is an attempt to shift attention away from poor management.

The two companies agreed in December on a deal valued at 14 billion dollars. US President Joe Biden and former President Donald Trump have both expressed their opposition.

Speaking at a Labor Day rally in Pittsburgh on Monday, Vice President Kamala Harris said, "US Steel should remain American-owned and American-operated."

Nippon Steel has said that US Steel's headquarters would remain in Pittsburgh if the deal is completed.

It promised to spend an additional 1.3 billion dollars to upgrade two plants and said Americans would make up a majority of the board of directors and form the core of management.