The Biden administration will reportedly pause a decision on approving what would be one of the world’s largest gas export hubs, amid concern from climate experts that greenlighting the project would create a “carbon mega bomb”.

The project, Calcasieu Pass 2, or CP2, would be positioned near the rapidly eroding Louisiana shoreline and be the biggest such export terminal in the US and part of a huge expansion of new gas infrastructure along the Gulf of Mexico.

The New York Times, citing three unnamed sources, reported Wednesday that the administration was pausing the decision in a delay that could stretch past the November election.

The move, the sources said, could spell trouble for the project and 16 other proposed terminals, as the energy department had been asked to expand its evaluation of CP2 to assess its impact on climate change, as well as on the economy and national security, the Times said.

The report comes as Joe Biden, who passed landmark climate legislation in August 2022 with the Inflation Reduction Act, and whose White House has been pushing funding boosts for electric vehicles in recent weeks, has disappointed climate activists who have been alarmed by US oil and gas production breaking records.

The report that the administration had paused CP2 was cautiously celebrated by environmental advocates. “It shows that the government recognizes the need to protect the rights and well-being of these communities,” said Roishetta Ozane, director of the Vessel Project, a Louisiana environmental justice group. “This decision would send a strong message that we can no longer allow fossil fuel industries to operate without considering the health and safety of the people living in these areas.”

Bill McKibben, the author and climate campaigner who has led opposition to CP2, praised the administration. “With this decision, President Biden – who already can claim to have done more to bolster clean energy than any of his predecessors – has also done more to check dirty energy, halting the largest fossil fuel expansion in history,” he said.

Some, however, cautioned that a pause would only be good news if it ultimately did not end up with approvals after the election. Wenonah Hauter, executive director of Food & Water Watch, said: “We don’t need new criteria if they only serve to arrive at the original conclusion, and increased exports are eventually approved. President Biden should permanently halt new and existing oil and gas exports, and aggressively ramp down the fossil fuel industry once and for all.”

One expert previously calculated that the CP2 project could create emissions that were 20 times greater than the controversial Willow oil project in Alaska, which was approved by the Biden administration despite a huge outcry from Democrats, Indigenous tribes and climate campaigners last year.

“This is a carbon mega bomb,” said Jeremy Symons, a former Environmental Protection Agency official, of CP2, speaking to the Guardian last October. “The scale of the project is almost unfathomable and it locks us into a fossil fuel dependency for the next 30 years. If all we do is shift from coal to gas, we are cooked.”

CP2 would ship up to 24m tons of liquified natural gas (LNG) each year once built.

Since Russia’s invasion of Ukraine in 2022, Biden has talked up plans to send LNG to Europe to help allies who had been reliant on Russian exports.

Environmental advocates have said that increasing US exports will undermine the country’s plans to transition away from fossil fuels. Advocates worry that the CP2 expansion will also exacerbate local environmental degradation and air pollution.

Emissions of carbon monoxide, sulfur dioxide and volatile organic compounds from LNG plants can exacerbate asthma and other respiratory conditions, cause headaches and skin irritation.

The project’s infrastructure could also contribute to Louisiana’s coastline crisis; the state’s low-lying coast has been subsiding due to sea level rise, caused by global heating, but also because of oil and gas development atop protective wetlands.

Venture Global, the company behind CP2, has said it plans a 30ft wall around CP2 to protect it from the rising seas, but experts have questioned the long-term viability of such infrastructure.

The company had hoped to start building by 2026, and is requesting a permit to operate until 2050, a point when Biden aims for the US to have zeroed out its emissions.

The firm has previously rejected criticism from climate experts. “The well-funded environmental activists opposing CP2 and all US LNG projects are completely out of touch with reality,” a spokesperson for Venture Global told the Guardian last year, adding that opposing utilities of its kind would “only result in continued and increased coal use and prevent the reduction of global emissions”.