President Donald Trump may finally be ready to cut some deals. After an embarrassing month that saw him unable to rally his own party around a health care bill, he appears to realize he can’t govern with Republicans alone. He has begun sidelining right-wingers like chief strategist Steve Bannon and elevating those who can bridge partisan divides and get things done. Nowhere is this more evident than in the rise of Gary Cohn, the former Goldman Sachs president and director of Trump’s National Economic Council. A registered Democrat, Cohn wields increasing influence over Trump and “is widely considered a future candidate to be chief of staff,” The Washington Post reported Thursday. Cohn reportedly is driven less by ideology than by a desire to make deals with the opposition party, which has led him “to show enthusiasm” for a carbon tax, “a Democrat-friendly idea which would raise revenue to ease tax reform, a top presidential priority, while also helping to curb carbon emissions.”

Many Republicans bristle at the idea of a carbon tax. The White House distanced itself from the idea this week after the Post reported it was under consideration, and many observers don’t think it stands a chance. “The most likely carbon tax is none,” Benjamin Zycher, an energy policy scholar at the conservative American Enterprise Institute, told me. “I think it’s simply a non-starter, both in the White House and on Capitol Hill.”

But some conservatives are on board with the idea—including Secretary of State Rex Tillerson, who has also reportedly gained high favor with the president. And if Trump really is prioritizing dealmaking with Democrats, then a carbon tax is not out of the realm of possibility. Tax reform, after all, is Trump’s next stated priority (when he’s not insisting that health care is still in the air, that is). And Democrats say they’re willing to come to the table, even if it means not getting everything they want out of a carbon tax bill. Congressman John Delaney of Maryland has introduced carbon tax legislation for the last two sessions, and says he’s willing to hear compromises. “I don’t expect my bill to come to the floor,” he said. “But if I were placing bets, I’d put a big one on the fact that we’re going to do a big deal on a carbon tax.” As Brian Schatz, a Democratic senator from Hawaii, tweeted this week:

There is a window on tax reform. But taxing groceries (VAT, BAT) is DOA. Taxing carbon would get a lot of Dem votes. A lot. — Brian Schatz (@brianschatz) April 11, 2017

In the simplest terms, a carbon tax is a fee that polluters pay the government for the damage their pollution causes the planet; companies would be charged per ton of carbon emitted. Depending on how the tax is structured, that money raised could go toward reducing corporate or income taxes. The money could also go toward programs that would lower energy bills for consumers, since a carbon tax would inevitably raise energy prices. Or it could go toward programs to help unemployed coal miners find new jobs (like Delaney’s bill does), or programs to further incentivize renewable energy. It all depends on how high the tax is, and who is deciding what it should do.

It’s hard to know exactly what a White House carbon tax would look like. (Neither Cohn nor Hassett returned my request for comment.) But we can glean some clues from its supporters. Cohn’s support for the policy has been echoed by Kevin Hassett, a tax expert at the conservative American Enterprise Institute who was tapped last week to be Trump’s chief economic advisor. Trump advisor Elon Musk, the SpaceX and Tesla CEO, and Secretary of State Rex Tillerson, the former CEO of Exxon Mobil, have also advocated for a national carbon tax policy in recent years.