Oct 25 (Reuters) - A Democratic proposal to impose a methane fee on U.S. oil and gas producers is not likely to be included in the party's massive spending bill amid opposition from within its own ranks, according to two sources familiar with the negotiations.

The proposal to tax oil and gas producers for methane emissions above a certain threshold faces opposition from U.S. Senator Joe Manchin, who represents West Virginia, along with Democrats from oil-heavy Texas, the sources said. (Reporting by Jarrett Renshaw; Editing by Leslie Adler)