After nine months and 350,000 signatures, and about a week before the deadline to submit those signatures, the organizers behind a revenue-neutral carbon tax–the “backup plan” to Governor Inslee’s failed attempt at a cap and trade system–have paused their march toward the ballot box. If they submit their petition, they could create a crippling schism in Washington’s climate change movement. If they don’t, 2016 could become another missed opportunity for climate policy.

“We are on the fence about whether or not to turn in our 350,000 signatures,” Carbon WA founder Yoram Bauman wrote on Monday, “because of the emergence of an alternative proposal.”

That alternative comes from the Alliance for Jobs and Clean Energy, an organization with strong ties to the Democratic party establishment. (The Alliance’s endorsement page is a who’s-who of well-known local political groups, and all of the Alliance’s money so far has come from lefty California billionaire Tom Steyer. The vast majority of Carbon WA’s donations, by contrast, come from within Washington, with a median donation of about $100.)

Alliance supporters have criticized Carbon WA for excluding minority groups, and because it is revenue neutral–that is, it would shift taxes from businesses and individuals onto major carbon polluters without increasing taxes overall. In a June Crosscut editorial, Rich Stolz of One America and Rebecca Saldana of Puget Sound Sage argued that any real carbon policy must not only discourage carbon emissions but also earmark funds to mitigate the effects of climate change on poor people who are most affected by it, such as migrant farmworkers. “Revenue neutral proposals,” they wrote, “like the initiative for which Carbon Washington is currently gathering signatures, fall short against these [social justice] criteria.”

Members of both the Alliance and Carbon WA camps have long insisted that this is a strategic disagreement between friends who fundamentally agree on the need for strong climate policy. But that hasn’t assuaged the fear on both sides, and among greens more generally, that a split in climate activists’ ranks will hobble the chances of moving legislation next year.

Hence Carbon WA’s hesitation to submit their signatures: pull the trigger, and they might shoot the climate movement in the foot. Don’t pull the trigger, and run the risk that no one else will, either.

To escape this dilemma, the two sides have been negotiating a compromise. If the Alliance puts forth a serious proposal for a 2016 climate initiative, and a serious commitment to pursue it, then Carbon WA may lay down its old signatures and join forces to gather new signatures for a joint climate initiative.

Alan Durning, executive director of the Sightline Institute (who once co-wrote a book with Bauman, and has worked with people on both sides), says he’s been “somewhat involved” in negotiations. “It’s been hard to find an agreement” between the two camps, he says, “but as of this week there is one.

“It’s not like this has been a highly structured series of summit meetings or something,” he says. “Lots of conversations and a lot of different people, all sort of coming to a head recently. And it’s as much a process of discovery, of gathering information and doing polling and talking to different legislators and sort of reporting back to each other.

“Think of it less as a tense negotiation between well-organized parties and more like a somewhat chaotic process of questions getting answered and new opportunities emerging.”

Part of the reason for the eleventh-hour hesitation at Carbon WA is new information. Bauman wrote, and Durning confirms, that new data shows the Alliance’s revenue-positive proposal significantly out-polls Carbon WA’s revenue-neutral, bipartisan proposal. (We haven’t yet been able to get a copy of that polling data, though it’s worth pointing out that early polls are often unreliable.) There’s also, says Durning, “much more information about what the Alliance will put before voters, there’s much more commitment to run an initiative, and there’s more information about the potential of the Alliance to raise the substantial sums necessary to overcome what is likely to be a huge counter campaign from the oil industry.”

Not everyone likes the idea of Carbon WA standing down at the last minute. Volunteers did, after all, put nearly a year of effort into gathering signatures, and switching from a revenue-neutral initiative to a revenue-positive one will make this policy less likely to spread to other states. Local weather scientist and occasional iconoclast Cliff Mass puts his support for the original Carbon WA proposal this way: “We would be the example of, not the Democrats shoving it through, but of a bipartisan group that does something. And by getting rid of this initiative, we’re basically throwing that away. Basically it becomes one political party in the hopes of getting a massive vote from King County to shove down the throat of the entire state. That’s not the example for the rest of the country.”

Of course, a bipartisan model isn’t much of a model if it can’t get voted into law. Durning says that Carbon WA leadership’s willingness to consider sacrificing their own campaign for the sake of strategically supporting the larger climate movement is a staggering example of “speaking unwelcome truths to a movement that you helped to build.”

“I see it as an act of extraordinary courage and leadership in the Carbon WA executive committee,” he says, “to suggest at this point to their supporters that there might be a better path by not filing. It’s almost unthinkable. If you think about all the momentum that builds up…to suggest at this late date that it would be better to join forces with the Alliance on a different carbon action plan shows to me tremendous leadership.

“For the agreement to [work], the key thing is that Carbon WA has to not submit its signatures, and that’s a giant decision for them. It is almost unprecedented to gather signatures and not file them,” he says.

Even if Carbon WA ultimately withholds its signatures and joins forces with the Alliance, its volunteers who’ve been beating the streets for signatures can claim credit for putting climate policy solidly on Washington’s 2016 legislative agenda. Says Kristen Eberhard, senior researcher with Sightline, “[Carbon WA] pushed forward. This would not be at the point that it’s at if not for the Carbon WA volunteers…They have created the momentum on this, and the question is, Can they get it over the finish line?”

Big Boi’s back up plan also differs from Carbon WA’s.