On the final day of his election campaign, Donald Trump stood on stage in Pittsburgh flanked by steelworkers and promised to protect American jobs and manufacturing. Curiously absent from his speech was his often-repeated promise to kill the sale of United States Steel to Nippon Steel.

The president-elect remains mum on the deal just as a top Nippon Steel executive readies a trip to Pittsburgh to persuade rank-and-file union members and politicians to support the $14.1 billion acquisition of the iconic American company.

Backing the deal would go against Trump’s campaign rhetoric, but the transaction has grown increasingly controversial among some steelworkers who represented critical working-class voters he had courted to win the crucial battleground state of Pennsylvania.