Via Climate Progress, E&E News reports that Sen. Barbara Boxer (D-Calif.), chairwoman of the Environment and Public Works Committee, is planning to introduce a climate bill Sept. 8, with a Republican co-sponsor:

Senate Environment and Public Works Chairwoman Barbara Boxer (D-Calif.) plans to unveil a major global warming bill immediately after Congress returns from the August recess, she said today….

Boxer predicted she would have at least one Republican co-sponsor on her bill, though she would not name names.

This last piece of news is potentially huge. Democrats have started giving up hope for bipartisanship on health care — to the chagrin of Republicans — but because a number of conservative Democrats are unlikely to vote for a cap-and-trade bill, it will be necessary to bring a few Republicans on board, at least to break a filibuster. A Republican co-sponsor could give cover to moderate Republicans — and fence-sitting Democrats — to vote for cloture, even if they have concerns about the political impact of a “yes” vote in the final tally.

If there is a GOP co-sponsor, it will most likely be Olympia Snowe or Susan Collins, the two moderates from Maine.