Exxon Mobil Corp and the United Steelworkers union (USW) reached a tentative agreement on the terms for workers locked out of a Beaumont, Texas, refinery for 10 months to begin returning to work in March, an Exxon spokesperson said.

USW Local 13-243, which represents the workers, has scheduled a vote on Saturday for members to ratify the agreement, said three sources familiar with the matter.

"We look forward to welcoming our employees back to work," said Exxon spokesperson Julie King.

Approval of the agreement would be the last step needed for Exxon to end the lockout, which it started on May 1, 2021, to avoid a threatened strike after the two sides could not reach agreement on a new six-year contract.

The refinery workers voted on Monday to ratify Exxon's latest contract offer, yielding to the company on a key demand that gave Exxon control over all job assignments in the 369,024 barrel-per-day (bpd) refinery and adjoining lubricant oil plant.

Under the return-to-work agreement, the nearly 600 workers would begin returning on March 7, the sources said. Most workers would be back in the refinery by March 11.

The return-to-work agreement does not require the USW to withdraw charges being investigated by the U.S. National Labor Relations Board (NLRB) alleging that Exxon started the lockout to force the union's removal.

The NLRB conducted a vote on removing the union in November and December, which had been requested by 30% of the locked-out workers. Ballots were impounded on Dec. 29 by the board as it investigates the charges.