In the nerve centre of the Trump resistance, some volunteers staff 24-hour hotlines in case immigration agents strike in the middle of the night. Others flood neighbourhoods to film arrests and interview witnesses. Local governments are teaming with donors to hire lawyers for those facing expulsion hearings.

California and the Trump administration are engaged in an all-out war over immigration enforcement, the president’s signature issue on the campaign trail and in the White House. It is a deeply personal battle in the nation’s most populous state, where 27 per cent of the 39 million residents are foreign born.

Attorney General Jeff Sessions last month filed a lawsuit accusing California, and its new slate of laws protecting immigrants, of violating the Constitution and endangering federal agents. In blistering remarks in the state capital, the nation’s top law enforcement official compared the actions of state and local officials to “secession” and a “radical open-borders agenda”.

But California is not backing down.

Donald Trump: 'if you don’t have a wall system, we’re not going to have a country'

In San Francisco, Mayor Mark Farrell called Sessions a “moron” and has proposed expanding the budget for public defenders. Sacramento Mayor Darrell Steinberg told public radio he would “proudly resist”. Oakland Mayor Libby Schaaf, who outraged the White House by warning her city about an impending immigration roundup last month, says she has no regrets.

“Local governments and state government have stepped up in a way to protect immigrants like never before in my lifetime,” says Eric Cohen, the 57-year-old executive director of the Immigrant Legal Resource Centre, a national nonprofit headquartered in the Mission district of San Francisco.

The stakes are high for the Trump administration because if California defies the White House on sanctuary cities, then others can, too, jeopardising Trump’s main campaign promise to deport many of the nation’s 11 million illegal immigrants. The administration has urged states to follow the lead of Texas, a state that passed a law requiring officials to cooperate with Immigration and Customs Enforcement (ICE) even as California enacted policies that do the opposite.

Oakland Mayor Libby Schaaf outraged the White House by warning her city about an impending immigration roundup (Christie Hemm Klok) (Photo for The Washington Post by Christie Hemm Klok)

California’s defiance marks a seismic shift in a state that has morphed from the nation’s biggest critic of undocumented immigrants a generation ago into their fiercest protector.

In 1994, nearly 59 per cent of voters passed Proposition 187, a ballot initiative that sought to deny public benefits to those here illegally and expel undocumented children from public schools. Outrage over the measure, which was blocked in court, helped turn a Republican stronghold into a mecca for Democrats.

Since then, California has granted undocumented immigrants privileges they can’t get in most other states: driver’s licenses, in-state college tuition and even some financial aid. After Trump took office and reversed Obama-era policies that shielded millions of undocumented immigrants from deportation, the resistance shifted into overdrive.

California filed lawsuits that have temporarily blocked the president’s plans to strip federal funding from so-called sanctuary cities and rescind work permits from undocumented immigrants who have lived in the United States since childhood.

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In January, this vast state officially became a sanctuary jurisdiction, restricting state and local governments from cooperating with immigration agents and warning employers that they could be fined if they voluntarily hand over workers’ private information to ICE.

Officials say they are not stopping immigration agents from arresting criminals and are making allowances so agents can take serious offenders into custody at state prisons. But ICE says California’s efforts put its workforce in danger, forcing agents to pursue criminals on the streets, often without local police backup.

After Schaaf tipped off her constituents to the roundup, agents arrested only 200 of more than 1,000 targets, a rate that Matthew Albence, executive associate director of ICE, calls “historically low”. Administration officials, including Sessions, blame Schaaf for letting the other 800 targets go free.

Albence says assaults on immigration agents in the streets and detention centres have risen from 15 three years ago to 69 last year. In the first two months of fiscal 2018, the agency logged 24 assaults.

“Frankly the environment’s gotten difficult across the board,” he says. “California is obviously front and centre with their sanctuary laws, making the whole state a sanctuary. But the job, by and large, has gotten more and more difficult and more and more dangerous for our officers.”

Schaaf says she has “tremendous respect for law enforcement”. The city worked with ICE in the past, she says, but severed ties with the agency amid concerns that its agents were ripping apart families whose only offence was coming to America in search of a better life. Officials also say they fear that ICE’s unfettered enforcement policies will make cities less safe by deterring undocumented immigrants who are not criminals from reporting crime.

In particular, Schaaf says, she is disturbed by the case of Maria Mendoza Sanchez, a bilingual oncology nurse, homeowner and mother of four who was forced to leave the United States in August with her husband, Eusebio.

“These are two law-abiding, hardworking Oaklanders that have lived in my city for 23 years,” Schaaf says. “But under this administration they were deported. They were ripped away from their four children.”

At a day labourer stand near a Home Depot in Oakland, immigrants waiting for construction jobs or grabbing lunch at a taco truck praise the mayor for sticking up for immigrants. “We’re here to work,” says a 36-year-old woman from Mexico frying meat at the taco truck, who declines to give her name for fear of being deported. “We’re not trying to hurt anyone.”

But the rising tension and vitriol have prompted some to ask whether Oakland and other cities are taking the resistance too far. The Los Angeles Times, which has defended undocumented immigrants in its opinion pages, said the Oakland mayor crossed a line when she tipped off the city about the roundups last month.

“Her heart may have been in the right place,” the newspaper wrote in an editorial. “But some of those targeted by ICE agents could very well have been people with violent criminal pasts who can make no legitimate argument for avoiding deportation.”

California sheriffs have said they feel caught in the middle and hope the federal lawsuit against the state will help settle the role they should play in enforcing immigration policy.

***

The Marin Rapid Response Network holds a meeting to train volunteers in San Rafael (Christie Hemm Klok) (Photo for The Washington Post by Christie Hemm Klok)

Nearly 20 volunteers eager to expand the resistance file into a conference room next to a bank in a nondescript office building in wealthy Marin County. They include a retired Presbyterian minister, a Vietnam veteran, and others who say they are upset by news reports they have seen of immigrants without serious criminal records being deported.

“I feel like I never really paid attention to politics until this past year,” says Jennifer Baldwin, a 46-year-old bookkeeper from the city of Novato. “It’s become a very painful world.”

Olivia Beltran, a former undocumented immigrant from Mexico who is now a US citizen, and Patty Hoyt, a Novato resident, help train volunteers willing to take emergency phone calls and investigate whether immigration raids are happening. Other volunteers venture out, even in the middle of the night, to document arrests and help those taken into custody find lawyers.

Hoyt says they would not interfere with law enforcement officers.

“You will be a witness,” she tells the volunteers. “Be brave. But be realistic.”

Jesus Alvarez, a 69-year-old navy veteran who served in Vietnam, signs up immediately. “It’s time for the community to rise up,” he says. “It’s time we defend ourselves.”