In a scathing letter sent by United Steelworkers to its members at US Steel Corp., the president of the labor group said the Pittsburgh-based company doesn’t prioritize its union workforce and accused it of betrayal.

In the letter seen by Bloomberg, USW President Tom Conway said workers cannot rely on management to put their interests first. “That’s why the contract we negotiated with US Steel contains strong protections that apply in this very circumstance,” Conway wrote.

The union plays a pivotal part in any transaction that involves the sale of US Steel mills or assets where the steelworkers are employed, and has been vocal about its exclusive support of Cliffs bid to buy the company.

The contract gives the union an opportunity to purchase US Steel assets in the event it receives any “bona fide offer” from a buyer. Conway last week advised US Steel and Cliffs that the union would transfer its legal right to launch a counteroffer for US Steel to Cliffs.

Read More: US Steel, Cliffs Spar Over Union’s Rights in Dueling SEC Filings

Cliffs CEO Lourenco Goncalves in 2019 and 2020 acquired AK Steel and ArcelorMittal USA assets, all of which had a heavy USW workforce presence. Goncalves famously kept all those jobs, promising not to close steel mills. It was a stark contrast from competitor US Steel which idled various assets over the years that resulted in union job cuts.

Conway in his letter pointed to US Steel canceling a $1.2 billion investment in the Mon Valley facility just outside Pittsburgh, and the company’s continuing effort to sell its blast furnace at Granite City to outsource production of pig iron instead of rebuilding the furnace for its own operations.

US Steel representatives were not immediately available for comment.