(Bloomberg) -- The United Steelworkers union formally endorsed President Joe Biden, a move that bolsters his campaign in crucial industrial swing states, and comes a week after he opposed the proposed sale of United States Steel Corp.

“President Biden proved time and again during his first term that he stands with working families,” USW International President David McCall said in a statement on Wednesday. The union also endorsed Biden for president in 2020.

The formal backing comes as the USW looks to block Nippon Steel Corp.’s plan to purchase US Steel for $14.1 billion. The deal, announced in December, has drawn strong opposition from the union and prominent lawmakers. 

Biden last week said US Steel should remain American-owned and run, a stance the union applauded. Biden has stopped short of explicitly pledging to block the deal, which is under review by the Committee on Foreign Investment in the United States, known as CFIUS. 

Earlier: US Steel Plunges for Second Day as Biden Comes Out Against Deal

Presumptive Republican nominee Donald Trump has promised to kill the sale. 

The deal has become a political flashpoint in the 2024 election, where Biden’s handling of the economy and jobs are taking center stage. US Steel is based in Pennsylvania, a key battleground state. 

Biden has heavily courted the support of organized labor, touting his administration’s efforts to create manufacturing jobs in the US and grow union ranks. While he has won the support of union leaders, he faces a tougher sell with rank-and-file workers.

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