HOUSTON, Jan 28 (Reuters) - Negotiators for Exxon Mobil Corp and the United Steelworkers union (USW) are discussing a contract proposal that could receive a ratification vote by workers locked out of a Beaumont, Texas, refinery since May 1, a union official said on Friday.

The members of USW Local 13-243 in Beaumont could vote on the contract proposal, if one is agreed to by negotiators, sometime in February, said Bryan Gross, USW International representative. (Reporting by Erwin Seba; Editing by Leslie Adler)