For Charles Hughes, climate change has been the backdrop of his entire life — from kindergarten lessons about disappearing habitats to the wildfire smoke that filled the air he breathed growing up in Colorado. Now a college student in Massachusetts, he says global warming rarely ranks as a top issue anymore.

“Honestly, it doesn’t come up as much,” said Hughes, who chairs the state’s chapter of the College Democrats.

Six years have made a striking difference. During President Donald Trump’s first term, and especially throughout the Democratic primaries that determined who would run against him in 2020, Democrats spoke constantly about climate change. They used it to rally young voters like Hughes, fueling protests and sweeping demands to remake the economy through proposals such as the Green New Deal, the 2019 congressional resolution — co-sponsored by Markey and Rep. Alexandria Ocasio-Cortez — that called for eliminating U.S. greenhouse gas emissions while creating millions of union jobs.

Since then, the national conversation has shifted so sharply that researchers have coined a term for it: “climate hushing.” The Searchlight Institute, a Democratic think tank, urged the party to stop mentioning climate change altogether because it is not a voter priority. The Sunrise Movement, a left-wing group that spent years promoting global warming as the defining issue for young people, switched its mission last fall to a broader mandate of fighting the Republican president.

The shift is encapsulated by Tuesday’s Democratic primary for U.S. Senate in Massachusetts, where incumbent Ed Markey, 80, is fending off a challenge from U.S. Rep. Seth Moulton, 47. Markey, first elected to Congress in 1976 and to the Senate in a 2013 special election, has long been one of the party’s most prominent climate voices. Although he still touts his sponsorship of the Green New Deal, his campaign now leans on other issues to burnish his left-wing credentials and to persuade voters he is not too old for the job.

It is the latest illustration of how climate change has been eclipsed by affordability, U.S. support for Israel and — above all — how to confront Trump.

“Six years ago, Green New Deal was every phrase out of Ed Markey’s mouth every chance he got. That is not the case now,” said Mary Anne Marsh, a veteran Democratic strategist in Massachusetts. “It’s about who’s best to fight. Period, full stop. Everything falls under that.”

The planet, however, has not quieted down even as the political discussion has. Scientists say there is a growing chance that by year’s end, 2026 could become the hottest year on record, or at least come close. A strengthening El Nino is forecast to be off the charts, pushing global temperatures higher.

Some advocates expect the issue to return to center stage if Democrats retake the U.S. House in November and climate-sparked disasters dominate the winter.

U.S. Sen. Sheldon Whitehouse of Rhode Island, a prominent Democratic voice on climate, said in an interview that ignoring the issue is a major strategic “blunder.”

“Climate change has moved from the science department into the economics department,” he said. “It’s now battering people’s home insurance, property values, pocketbook concerns. So I think it’s a very powerful argument.”

Trump has falsely claimed that climate change is “a hoax,” and his party has regularly scoffed at Democratic proposals such as the Green New Deal.

The Sunrise Movement, founded in 2017 to mobilize young voters around climate issues, announced in October that it was pivoting to a broader fight against “fascism.” Executive Director Aru Shiney-Ajay called that a prescient move, citing reports that federal agents infiltrated protest meetings during Trump’s immigration raids in Minneapolis.

“We just live in a significantly more authoritarian country. Because of that, a lot of the Democratic primaries are about more existential questions,” Shiney-Ajay, whose network generally backs left-wing Democrats, said in an interview. “It has felt less like people care less about climate and more like people are increasingly freaked out about other issues.”

About 6 in 10 Democrats say climate change is “a very big problem” for the country, according to a Pew Research Center poll from April — roughly the same share as in 2016. Even so, climate has frequently taken a back seat to other priorities among Democratic voters, such as inflation, healthcare affordability and the role of money in politics.

Affordability concerns have dominated this year’s political debate. McKenzie Wilson of Blue Rose Research, a Democratic data firm, said voters are demanding sweeping change in response to economic discontent, showing a level of anger not seen in years.

“In that kind of environment it’s hard to think about long-term, existential problems,” Wilson said. “If we don’t talk and focus our attention on the number one thing the electorate wants to talk about, as we saw in 2024, we’re not going to be connecting with the electorate.”

That view was summed up by the Searchlight Institute, which last year released a provocative recommendation: “The First Rule About Solving Climate Change: Don’t Say Climate Change.” The think tank argued that voters see the issue as so intimidating and complex that Democrats are more likely to win by campaigning on other subjects — thereby positioning themselves to regain power and tackle the very crisis they were not discussing.

Leah Stokes, a political scientist at the University of California, Santa Barbara, and author of “The Carbon Wave,” a book about Democratic President Joe Biden’s domestic agenda, said it is “galling” when politicians deprioritize the issue.

“The climate crisis is accelerating and we can’t really not talk about it for like a decade, because the planet will be even more on fire if we do that,” she said.

Anthony Leiserowitz, director of the Yale Program on Climate Change Communication, echoed those concerns.

“What happens over the course of the next decade will profoundly shape the habitability of the planet for literally thousands of years to come,” he said.

Climate has surfaced as part of the national backlash to data centers, whose surging electricity demand has stirred local opposition across the country, but it represents only one strand of the conversation about those projects’ impact. Many climate advocates are recalibrating how they talk about the issue, emphasizing how green energy can lower prices and ease insurance costs.

“What we’re seeing right now is, whether you’re advocating for healthcare reform or climate action or some niche tech issue, everything is filtered through some cost frame,” said Jared Leopold, a veteran Democratic strategist who has long focused on climate change.

That framing shaped how the Green New Deal surfaced at a recent debate between Markey and Moulton, when a voter asked how each candidate would reduce energy prices. Notably, the questioner raised increasing nuclear or gas generation — not clean energy — to address costs. Markey seized the moment to slam the president.

“There was a plan in place in order to have a strong, clean affordable energy future for our commonwealth,” Markey said, “and Trump attacked it.”

Tatishe Nteta, a political scientist at the University of Massachusetts Amherst, said that dynamic captures how Markey has deployed climate change this election cycle — as a signal of his willingness to fight Trump and of his alliance with the left flank of the Democratic Party, which has notched a series of primary wins this year. But other issues have become even more useful for that purpose.

“The definition in where you’re at in terms of a progressive candidate and a progressive elected official is your viewpoint on Israel,” Nteta said. “You’re not hearing this in most races, that I’m the candidate who’s going to protect and save our planet.”

For Eileen Cefail, this Massachusetts summer has been the hottest she can recall in the 30 years she has worked at the Roofers Local 33 office. “The roofers are tough as nails, and they work so hard, and their work is so grueling,” she said. “This heat has been horrendous for them.”

Cefail is backing Markey in the primary, but climate, she said, was not the main reason.

“He’s always been a union guy,” Cefail said. “He’s just for the labor.”

This story was originally featured on Fortune.com.