HOUSTON, Oct 8 (Reuters) - The labor union representing workers locked out of a Exxon Mobil Corp (XOM.N) refinery on Friday accused the oil firm of trying to "bust our union" by supporting efforts to officially remove the union with a decertification vote. Any vote would be tainted by "serious unfair labor practices," the USW said in a statement that accused Exxon of "misleading people with confusing statements regarding our union, our negotiations and the company"s spiteful lockout." A majority of the plant"s union members "are still with us," Bryan Gross, a USW international representative, said of a vote"s prospects. Exxon locked out 650 union workers from its Beaumont, Texas, plant on May 1 after the prior contract expired and there was no vote on the company"s proposed offer. The refinery, which makes gasoline and Mobil 1 motor oil, has continued to operate using managers and replacement staff. The U.S. National Labor Relations Board this week said it had received a petition backed by signatures from at least 30% of workers represented by United Steelworkers union local 13-243, the minimum required to call for a decertification vote to remove the union. If the Beaumont employees approve a decertification, it would remove the USW as their bargaining agent. There is no timetable set for when a vote could occur. Exxon has said its contract proposal contains provisions needed to ensure flexibility to compete in low-margin environments. The company stepped up its efforts to win a vote, accusing the union of sowing misinformation and engaging in voter suppression on the decertification effort. read more The USW has said the proposal would wipe out important worker seniority protections and, by creating separate contracts for the plant"s refinery and lubricant oil plant employees, dilute their negotiating power. USW and Exxon negotiators met on Friday, Gross said. "The company clarified some things," he said. "We gave them a few things to consider."