A statement from Esmark's board says it's not convinced Severstal could close the deal.
Board members also say it's not in the best interests of shareholders and urged them not to sell their shares to the Russian metals and mining company.
The United Steelworkers is supporting Severstal's bid, but it did not immediately comment.
Esmark Chief Executive James Bouchard (boo-SHARD') says Severstal is welcome to improve its bid.
Esmark has operations in 20 states, including subsidiary Wheeling-Pitt plants in West Virginia, Ohio and Pennsylvania and a plant in Greensville County, Va.
