Oren Cass, a senior fellow at the Manhattan Institute and the domestic policy director of Mitt Romney’s 2012 presidential campaign, said he was grateful that a carbon tax never made it into the bill.

“The long and the short of it is, I don’t think a carbon tax is either good climate policy or good fiscal policy,” he told me. “Even the pretty strong proponents of the carbon tax, they don’t try to assert that it will do anything about climate change. And if you ask them to provide any benefit estimate that they could put into analysis, they won’t—you’ll get vague talk about leadership, or how it’s going to spur innovation.”

But he also resented that the Republican tax bill in its final form increased the deficit by more than $1 trillion. “I dislike strongly that the tax cut is not revenue neutral,” he told me. “I think if you want to cut taxes, you should find other taxes you want to have to pay for it. But if you were to plot out a list of all the revenue raisers you could have, I think a carbon tax should be very far down the list.”

Why? Because carbon-dioxide emissions make for a “terrible tax base,” he said. If a carbon tax succeeded in reducing the use of fossil fuels, or forcing people to move to renewable energy, then it would erode its own tax base over time. “You’ve shifted onto an unstable tax base that you’re hoping will go away, and you’ll wind up having to raise other taxes up anyway” He also said a carbon tax imposed regressive penalties on sectors and regions already struggling in the current economy—such as energy-intensive manufacturing in the Midwest—while rewarding “higher-income coastal knowledge work.”

The massive unpopularity of the Republican plan—41 percent of Americans believe it is a “bad idea,” according to a Wall Street Journal/NBC News poll—may now give Democrats the opportunity to pass their own tax bill. Adam Looney, who led tax analysis at the U.S. Treasury Department for the last three years of the Obama administration, predicted at an event last month that the tax code would continue to change in the years to come.

“It also seems like this is not going to be the last word on tax reform. There will be a lot of changes yet to come in the tax system,” he said. “The carbon tax will always be right there on the shelf ready for the right moment.”

Gerrard, the Columbia University professor, agreed, saying that the Republican carbon-tax plan from February isn’t dead yet. “If, for instance, we have Democratic control of Congress [in 2020 or 2024], then that proposal could attract the moderate Republicans who are now keeping their heads down in the foxhole,” he told me. (Though that assumes that Democrats would reintroduce a Republican-invented plan.)

But even if the pipe dream of a bipartisan carbon tax has ended for now, the effort to bring Republicans over to the fold will never die. The Climate Solutions Caucus, a bipartisan group of House legislators, recognizes the existence of global warming and “explores policy options” to research it, slow it, and prepare for it. Membership must be kept even between Democrats and Republicans—meaning, in essence, that a Democrat can only join when they woo a Republican to hop in, too.