SAN FRANCISCO — Democratic National Committee members shot down an effort to hold a climate change-focused presidential debate Saturday, in a victory for party leadership and a defeat for activists demanding a stronger focus on the environmental crisis.

Party delegates voted 222 to 137 against allowing candidates to participate in a debate dedicated to the topic, after a heated floor fight interrupted by protesters chanting “We can’t wait!” and “Failure of leadership!”

The bitter dispute at the party’s annual summer meeting in San Francisco threatened to reignite criticism on the left that Democratic leaders are squelching debate on one of the most important issues to young voters. And the delegates opposed a climate debate even though many of the presidential contenders have come out in favor of one.

The vote came at a time when world leaders are ringing the alarm over massive fires in the Amazon rainforest — a disaster pointed to repeatedly by activists to stress the dire threat climate change poses.

“If an asteroid was coming to earth, there would be no question about having a debate about it,” argued Chris Reeves, a DNC member from Kansas. “But with this existential crisis facing the world, we all sit and wring our hands.”

CNN and MSNBC are hosting two presidential forums on climate change next month, at which the candidates will speak individually on the topic. But activists say that isn’t enough: They’re demanding a head-to-head debate among the White House hopefuls, which they argue would give the climate crisis the attention it deserves.

Party leadership, including DNC chair Tom Perez, strongly opposes the idea, insisting it would be unfair to elevate one issue over others.

On Saturday, the battle focused on a resolution approved by a party committee two days earlier that would essentially open the door to presidential contenders participating in a climate debate. Perez moved to scrap that proposal Saturday, saying the party should preserve rules prohibiting candidates from debating one another face-to-face outside of a dozen official party-hosted events.

“We want to make sure we don’t change the rules in the middle of the process,” he said. “We have a North Star principle: We want to be fair to everyone.”

The debate over the issue was punctuated by chants and jeers from several dozen climate activists, who crowded into the back of the hotel ballroom where the vote took place. Proponents emphasized the urgency of the crisis, pointing to devastating wildfires and floods in their own states and around the world.

“The Amazon is burning today — I don’t mean Amazon in Seattle, I mean Amazon in Brazil,” said Tina Podlodowski, the chair of the Washington State Democratic Party. “We will never get this back.”

Opponents of a debate agreed climate change is an existential threat but said it didn’t make sense to elevate the environmental crisis over other key issues, like gun violence, immigration or white nationalism.

“Think about the fact that they’re gunning down people who look like me out on the streets,” said Alma Gonzalez, a DNC member from Florida. “I would love to have a debate on the fact that we have domestic terrorism in this country.”

Others said that opening the doors to more debates beyond the 12 already planned by the DNC would force candidates to spend more time in preparing for the events instead of meeting voters and organizing supporters on the ground.

“It will take away time from their knocking on doors, going to all of your states to be able to campaign,” insisted Maria Cardona, a political strategist and DNC member from Washington, D.C.

Young activists with the climate-focused Sunrise Movement filled the halls of the Hilton Union Square Hotel during the meeting this week, holding a sit-in and dropping a banner urging support of a climate debate Friday.

Twenty presidential candidates also publicly supported such an event, according to a tally by pro-debate activists, and several of the contenders who spoke at the meeting Friday mentioned the issue in their speeches to delegates. Former Vice President Al Gore also joined in on the calls.

“This decision is as baffling as it is alarming,” presidential hopeful Beto O’Rourke tweeted after the vote. “Our planet is burning— the least we can do as a party is debate what to do about it.”

Activists said they planned to pressure television networks hosting future primary debates and forums to ask tough, substantive questions on issues like phasing out coal, building pipelines and putting the Green New Deal proposal into action.

“It shatters the trust the party is so barely holding onto,” said Jasper Wilde, a 29-year-old activist from San Francisco. “Young people are going to see this as another reason they shouldn’t believe in the Democratic Party.”