WASHINGTON  —  The former chief of staff at the Department of Homeland Security claims in a political ad released Monday that President Trump tried to withhold disaster relief money for California’s wildfires because voters in the state opposed him politically.

“He told us to stop giving money to people whose houses had burned down from a wildfire because he was so rageful that people in the state of California didn’t support him and that politically it wasn’t a base for him,” Miles Taylor, who left the Trump administration in 2019, claims in the ad.

“A lot of the time, the things he wanted to do not only were impossible but, in many cases, illegal,” Taylor said, recalling how Trump “didn’t want” to hear aides inform him that his policies wouldn’t stand up to legal challenges.

“These were his words: He knew that he had ‘magical authorities,’” Taylor said, recalling a phrase he said Trump used to brush off questions from aides.

The Department of Homeland Security oversees the Federal Emergency Management Agency. Taylor doesn’t say which wildfires he is referring to, but the group running the ad confirmed it was the Camp fire of 2018, and Trump toured the devastation in Paradise that year.

No evidence has surfaced to show that federal aid was withheld, despite public threats from Trump at the time, who said he would withhold money because he disapproved of the state’s forest management practices.

Taylor took a job at Google after leaving the Trump administration and is on leave, according to his Twitter profile.

The two-minute ad, promoted by a group called Republican Voters Against Trump, follows sharp criticism from several former top White House aides and others, including former National Security Advisor John Bolton, who have questioned Trump’s fitness to serve a second term.

The ad was released on the first day of the Democratic National Convention, which will nominate former Vice President Joe Biden to run against the incumbent.

In the video, Taylor calls his 2½ years in the Trump administration “terrifying” and says that, although he disagrees with Biden on many issues, he is “confident Joe Biden will protect the country. I’m confident he won’t make the same mistakes as this president.”

The White House quickly fired back.

“This individual is another creature of the D.C. Swamp who never understood the importance of the president’s agenda or why the American people elected him and clearly just wants to cash in,” said Judd Deere, a White House spokesman.

A senior administration official questioned why Taylor served so long if he had such qualms about Trump. The official also pointed to Trump’s public threats to withhold money and the fact that the money was not ultimately withheld.

Gov. Gavin Newsom declined to comment.

The allegation that Trump tried to stop California from getting FEMA assistance serves as the most emotional attack on Trump’s leadership in the testimonial. But there are others.

“We would go in to try to talk to him about a pressing national security issue — a cyber attack, terrorism threat — he wasn’t interested in those things. To him they weren’t priorities,” Taylor says of Trump.

Taylor recalled how Trump “wanted to go further” with his family separation policy to send a stronger message of deterrence to would-be asylum seekers fleeing Central American countries for the United States.

“I came away completely convinced, based on firsthand experience, that the president was ill-equipped and wouldn’t become equipped to do his job effectively,” Taylor says, explaining his decision to support Biden despite continuing to identify as a Republican. “And what’s worse — was actively doing damage to our security.”

Taylor worked under acting Homeland Security Secretary Elaine Duke, who briefly held the job in 2017 after former Gen. John Kelly left the post for the White House and before the Senate confirmed Kirstjen Nielsen, the last non-acting head of the third-largest federal department.

Taylor was deputy and chief of staff to Nielsen, who oversaw the implementation of the administration’s family separation policy for migrants on the border.

Staff writers John Myers in Sacramento and Molly O’Toole in Washington contributed to this article.