Arcelor Mittal, which operates a plant in Steelton, is idling some operations at its Conshohocken plant outside Philadelphia, laying off at least 150.

Arcelor Mittal Conshohocken

United Steelworkers Union Local 9462 announced the layoff Monday, saying at least 200 will lose their jobs, Philly.com reports.

Arcelor Mittal is idling its rolling mill at the Conshohocken plant, and the layoffs will take place over several months, said Mary Beth Holdford, company spokeswoman. An implementation plan is still being developed to determine when the layoffs will start, she said.

Arcelor Mittal's web site says the facility employs 265 at its plate production facility along the Schuylkill River.

The union blames inaction by the Trump administration on steel imports for the layoff.

"Many steelworkers being laid off at this facility proudly wore the uniform and are dedicated to making vital equipment for our troops. The administration's refusal to act is just another sign that the Washington swamp has not been drained; it is business as usual. The White House needs to get its priorities straight," said Thomas M. Conway, USW International vice president.

Holdford said the company will idle the operation at the Conshohocken plant within the next year, due to limited demand from key manufacturers that build bridges, ships, tank cars and military equipment, along with the "ongoing surge of unfairly traded imports of steel."

The Conshohocken plant will continue to operate its heat treat, finishing and inspection facilities to finish steel rolled by its sister facilities in Coatesville and Burns Harbor, Ind. It was not immediately known how many jobs will remain to do that work.

There are no plans for more layoffs at Arcelor Mittal's Steelton plant, Holdford said.

The plant laid off about 85 people after going to a single crew in early March, she said. But some workers were recalled due to fill slots open through attrition.

The Steelton Arcelor Mittal plant employs about 538, and is one of only three rail producers in North and South America.

Holdford said the layoff at the Conshocken plant is unrelated to the Steelton facility, and they produce different products.

UPDATE: The status of the Conshohocken plant and timeline of layoffs was corrected in this story.