As wildfires erupted in Southern California, so did a years-long feud between incoming president Donald Trump and Gov. Gavin Newsom.

On the campaign trail, Trump repeatedly threatened to cut off disaster funding for California.

He stopped short of that on Wednesday, but in a social media post, he called Newsom “Newscum” and blamed his water policies for the three fires that have destroyed hundreds of homes, killed at least five people and displaced tens of thousands of Californians. Due to environmental regulations, he said, not enough water has reached Southern California and fire hydrants went dry as a result.

“Now the ultimate price is being paid,” he said. “I will demand that this incompetent governor allow beautiful, clean fresh water to FLOW INTO CALIFORNIA. He is to blame for this.”

The Newsom administration called Trump’s post “pure fiction.” Climate and wildfire specialists say eight months of drought — and blowing embers driven by Santa Ana winds gusting as high as 75 mph — are to blame.

“You’ll never have enough water to put out a Santa Ana fire,” said Zeke Lunder, a California wildfire expert who’s been tracking and mapping the fires’ progress.

The bigger question looming over California is whether Trump’s feud with Newsom will cause him to act on his promise to cut federal disaster aid to the state when he takes office on Jan. 20.

On the campaign trail last year, Trump vowed that “we won’t give (Newsom) money to put out all his fires” unless the Democratic governor agreed to divert more water to California farmers. Two former Trump administration officials later told Politico that Trump initially withheld approval for disaster aid for California’s deadly 2018 wildfires, until aides showed him that many of the residents of the affected areas had voted for him.

A president can slow down the process of approving aid, or not declare a disaster, a decision critical to a state receiving federal relief funding. A 2021 federal report found that the Trump administration delayed $20 billion in disaster aid to Puerto Rico after Hurricane Maria in 2017.

Federal funding typically pays for around 75% of the costs of rebuilding public infrastructure such as roads, sewers, water systems, parks and fire stations, officials say. That means California would have to come up with billions of dollars in additional money after major disasters if Trump follows through on his campaign rhetoric.

Federal disaster funds also help those who’ve lost their homes find temporary living quarters. Federal programs can help with home-rebuilding costs not covered by private insurance.

Newsom preparing for uncertain disaster funding

Newsom has taken Trump’s threats seriously enough that, in the fall, his administration began developing plans to establish a backup emergency response fund that the state could draw from if Trump refused to make federal aid available. It’s unclear if Newsom will follow through with the idea in his formal budget proposal, which is expected Friday.

“What you see with the president-elect is, you know, fire and fury often signifying something. You see fire and fury often signifying nothing,” Newsom said at a press conference Monday, where he cautioned that California’s fiscal stability is uncertain under the incoming Trump administration. “And you have to sort of work through all of that.”

On Wednesday, the outgoing Biden administration pledged federal help and is already sending disaster aid to the state, thanks to the $100 billion Congress approved in December.

President Joe Biden, who was already in California to designate a new national monument and for the birth of his great-grandson, made a brief public appearance at a Santa Monica fire station on Wednesday morning to pledge his support for the response.

“We’re prepared to do anything and everything, as long as it takes, to tame these fires and help reconstruct and make sure we get back to normal,” Biden said. “It’s going to be a hell of a long way. It’s going to take time.”

Newsom, who joined Biden, said the president’s quick declaration of a major disaster “means the world to us.”

“It’s impossible for me to express the level of appreciation and cooperation we received from the White House and this administration,” Newsom said. “So on behalf of all of us, Mr. President, thank you for being here. And not just being here today. Thank you for being here since the minute of this incident.”

Most of California’s congressional delegation — including U.S. Sens. Alex Padilla and Adam Schiff and 47 House members, both Democrats and Republicans — signed onto a letter urging Biden to approve the declaration Wednesday.

“The severity of these wildfires requires additional coordination and a wider range of long-term federal recovery programs,” the lawmakers wrote.

When asked Wednesday about Trump’s past threats to withhold disaster aid to California, Padilla warned that “our response to these disasters cannot become a partisan issue, and I will continue fighting to secure the necessary resources for our state’s recovery.”

How federal money rebuilt Paradise, Santa Rosa

In communities such as Paradise and Santa Rosa that suffered through similar catastrophic fires within the past decade, officials there said their communities wouldn’t have been able to rebuild without federal help.

“If we hadn’t had those types of funds to do the basic infrastructure that we’ve already done and are currently doing, I don’t think we would have recovered at all. It is such a significant piece of recovery,” said Collette Curtis, the recovery and economic development director for the town of Paradise. An early morning fire on Nov. 8, 2018 pushed by powerful winds destroyed most of the town in a matter of hours. Eighty-five people died; 18,000 buildings were destroyed.

Curstis estimates that Paradise has received at least $375 million in federal aid since the fire.

A year before the Paradise fire, thousands of homes in the city of Santa Rosa and surrounding communities burned in the Tubbs Fire – another wind-driven inferno that killed 22 people.

The federal government provided at least $366 million in direct aid to communities affected by the Tubbs Fire and other fires that year, according to estimates from the office of U.S. Rep. Mike Thompson, a Democrat who represents the region. Santa Rosa alone received $218 million, said Assistant City Manager Jason Nutt.

Without that much federal help, Santa Rosa wouldn’t have recovered, said the city’s former mayor, Chris Rogers, who was just sworn in as the region’s Democratic Assemblymember.

“Without the help of the federal government, not only would we potentially not have been able to rebuild, but we certainly wouldn’t have been able to rebuild as quickly,” Rogers said.

Rogers called Trump’s threat to cut disaster funding for California communities “inhuman.”

“This is a time when people need the most support, when they’ve lost everything,” Rogers said. “That’s the time when they need government to function for them. And so, to me, it’s completely unconscionable that you would choose that as not just to make a statement, but as a leverage point to try to get other things that you want. It’s wildly inappropriate.”

Ryan Sabalow and Alexei Koseff are reporters with CalMatters. CalMatters reporters Stella Yu and Alastair Bland contributed to this story.