Democratic senators for about a year have been negotiating with Manchin to try to get him on board with investments that would dramatically reduce U.S. contribution to climate change.

But on Friday, Manchin said he’s not interested in immediately moving forward with a deal that includes those investments.

Manchin told West Virginia radio host Hoppy Kercheval that the latest inflation data means it’s “not prudent” to make the investments in climate change — or raise taxes on the wealthy.

Manchin, relaying a discussion he’d had telling Majority Leader Charles Schumer (D-N.Y.) of his decision, suggested he might be able to agree to a deal at a later date.

“I said, ‘Chuck, can we just wait until the inflation figures come out in July?’” he said. “I want climate. I want an energy policy.”

But those comments rang hollow with climate activists, who noted he has made similar remarks in the past.

“Joe Manchin is waving the fate of human survival over our heads like a bone to hungry dogs and it’s really quite frightening,” John Paul Mejia, a national spokesperson for Sunrise Movement, told The Hill.

Evergreen Action Executive Director Jamal Raad said in a statement that Manchin should not be considered a good-faith negotiator.

“Senator Manchin has lost all credibility and can no longer be trusted to prioritize the well-being of Americans and the planet over his own profiteering and political grandstanding,” Raad said.

Democrats, activists and scientists reacting to the news worried that the inability of Congress to take meaningful reaction would consign the U.S. to more heatwaves, floods, droughts and intense storms.

With Republicans seemingly poised to win back the House majority this fall, Manchin’s decision felt like a death blow to the hopes of taking action on climate with Democrats in the White House and in charge of both chambers of Congress.

“Every ton matters,” said Dan Lashof, the U.S.director of the World Resources Institute, referring to tons of carbon emissions.

“Whether or not this bill gets done has a material impact on total emissions from the U.S. and that affects the magnitude of climate change that we will face,” he said.

Those who have studied the climate-saving potential of the Democrats’ climate bill agree that not passing it would likely lead to more emissions and a warmer planet.

Princeton professor Jesse Jenkins, who has modeled the potential emissions cuts of the legislation under consideration, told The Hill that based on what had been reported thus far, a climate deal would have probably cut emissions between 800 million and 1 billion metric tons in 2030. That’s the equivalent of taking between 172 million and 215 million cars off the roads for a year.

“We’re losing two-thirds to three-quarters of the progress we were hoping to make by 2030,” he said.

Robbie Orvis, senior director of energy policy design at the think tank Energy Innovation: Policy and Technology, also said the emerging bill could have cut emissions as much as by 1 billion tons.

“The probability of being able to hit the 2030 target is much lower now, so I think that implies that there will be more emissions, certainly, and that translates to higher warming,” Orivs said, referring to President Biden’s goal of cutting emissions in half by the end of the decade.

“Every amount that we continue to increase the global temperature brings more extreme storm events,” he said, adding that without action, “we’re going to continue to worsen the impacts of climate change, and it’s going to contribute to worsening extreme weather events and … ultimately human suffering and death.”

Biden pledged “strong executive action” on climate change in reaction to Manchin’s move.

But observers say it will be very difficult to reach the same goals without legislative action.

“Sure there’s probably a way to get there if you assume a whole bunch of things go right and are defensible in court, but it certainly makes it much, much harder,” Orvis said.

Some on Friday argued that the rest of the world may be less inclined to take bold action without the U.S. participating as well.

“The U.S. is THE largest historical all-time emitter, and for that reason occupies a special role. We can’t expect other countries to act meaningfully if we fail to,” said climatologist Michael Mann in an email to The Hill.

Jenkins added that not passing the bill is also expected to stifle technological innovation, hampering the global transition to clean energy.

David Victor, a professor at the University of California, San Diego took a slightly different view, arguing that a major climate deal has been unlikely since the get-go and that at least now the public can move ahead with some clarity.

“I think what you’re going to see is a lot more action in the states [and] a lot more action…sector-by-sector,” Victor said.

Most activists reacted in fury to the latest setback, castigating the West Virginia Democrat as potentially signing a death warrant for meaningful climate action against the backdrop of a generationally conservative court, the likely loss of a Democratic majority in Congress and the possible loss of the White House in 2025.

Raad said the inflation report was a convenient excuse that elided Manchin’s history of backing out of talks.

“Joe Manchin has pretended to be supportive of certain investments for over a year now, and it turns out that that was bulls—,” he told The Hill. “That will now be his lasting legacy — a person that tried to put his own profits and sense of his political standing over the planet.”