By Erwin Seba

HOUSTON (Reuters) -The U.S. National Labor Relations Board on Wednesday impounded ballots that will decide whether the United Steelworkers (USW) continues to represent workers at an Exxon Mobil oil refinery in southeast Texas, according to the union and company.

The NLRB has said it may impound the ballots while it reviews complaints filed by the USW union alleging Exxon barred workers from its Beaumont, Texas, plant on May 1 to break the union. The USW also charged the decertification campaign was improperly supported by the company.

Exxon spokesperson Julie King said the company was told by the NLRB on Wednesday morning the ballots had been impounded and would not be counted until further notice.

“Exxon Mobil remains confident that it has acted in accordance with the law at all times, and the NLRB will dismiss these charges once they have completed their investigation,” King said.

USW International Representative Bryan Gross said the local hopes Exxon “will end the lockout and get back to the table.”

About the board’s action, Gross said, “We believe that’s a positive. They’ve got enough evidence in our information and affidavits. We hope this lets the company know they need to get back to the bargaining table.”

Exxon locked out union members from the 2,700-acre Beaumont, Texas, refinery and lubricant oil packaging plant on May 1 after contract talks failed to produce a new agreement. The facility produces fuels and Mobil 1 motor oil, and has continued to run with managers and replacement workers.

The eight-month-long lockout will end if the about 600 union-represented workers vote to remove USW local 13-243 in Beaumont as their negotiating agent or accept the company’s last contract offer, Exxon has said. Local 13-243 members rejected the contract offer in October.

The refinery has continued to operate with managers and supervisors from around the nation at its controls. Exxon has said the 369,024 barrel-per-day (bpd) refinery is operating at maximum capacity.

Ousting the union would require a 50%-plus-one share of votes cast. However, the NLRB had warned it might impound the votes pending its finding on the union’s allegations that Exxon improperly supported the effort to remove the USW.

Exxon proposed a contract with terms it said would allow the plant to be competitive in low-margin environments. The union has said it wants to keep provisions that give workers a say in job assignments.

Negotiators have agreed to some parts of a possible contract, including a six-year term and pay increases that would match those to be set by national USW contract talks that begin in January.

Workers were locked out at Beaumont because of a strike notice issued by Local 13-243, Exxon has said. The strike notice “could not ensure safe continuous operations with the union being able to strike anytime with only 24 hours notice,” it said.

The USW said Exxon was preparing to lock out workers before the strike notice, pointing to portable housing for replacement workers installed inside the Beaumont complex in the weeks prior to the lockout.

During the lock-out, the number of workers at the refinery represented by the USW has dwindled from 650 to about 580, as workers took jobs at other refineries or chemical plants in the region, people familiar with plant operations said.

(Reporting by Erwin SebaEditing by Chris Reese)