A WAR is raging on many fronts between the Trump administration and America's most populous state, California, typifying a deep divide stretching across the nation.
Democrats, who hold the majority in both houses of the state's legislature, are on a mission to strike down the President's policies in areas as wideranging as immigration, taxes, the environment and recreation marijuana.
Washington watchers also note that, almost a year into his presidency, Mr Trump is yet to visit California. If he doesn't hop on over to the west coast before next Saturday, he will be the first president since Dwight Eisenhower 64 years ago not to visit the state in his first year in office.
Mr Trump is unpopular in California, which is home to almost 40 million people and is an economic powerhouse. A December poll found that 57 per cent of Californians "strongly disapproved" of the President and only 30 per cent approved.
And while he won the presidency without the support of California - Hillary Clinton trounced him there - the state's vehement opposition to his policies is beginning to cause major headaches in Washington DC.
It's an interesting conflict that pits a progressive state standing up for its rights against a nationalist president trying to "make America great again".
"The fight has metastasised into what could be the greatest contest over values between a White House and a state since the 1950s and 1960s, when the federal government moved to end segregation and expand civil rights," The New York Times wrote this week.
With so many federal policies going against California's wishes, senate leader Kevin de Leon said President Trump is waging a "war on California".
Here are the battles that California is fighting against the commander-in-chief.
With a 40 per cent Latino population, a lengthy border with Mexico and an estimated 2.4 million undocumented immigrants, California is ground zero for America's divisive debate on immigration.
Mr Trump won power promising to build a wall along the border and to halt illegal border crossings. The President has also expanded the powers of Immigration and Customs Enforcement (ICE) - the US equivalent of the Australian Border Force - empowering officers to deport undocumented immigrants.
Most Californian cities - most notably San Francisco and Los Angeles - have declared themselves as "sanctuary cities" which deliberately discourage co-operation with immigration officers.
Mr Trump has said sanctuary cities "breed crime" and he seized on the policy when an illegal Mexican immigrant shot dead 32-year-old woman Kate Steinle in San Francisco in 2015. The gunman had been deported from the US five times before the shooting.
Despite this controversy, Californian politicians and mayors maintain that deporting undocumented immigrants who are otherwise law-abiding would be bad for the state.
ICE acting director Thomas Homan said the stance was "terrible" and "foolish", and implied that the politicians who supported it should be arrested.
"You have a state of California that wants to put politics ahead of public safety, ahead of offshore safety," he told Fox News.
"California better hold on tight. They're about to see a lot more special agents, a lot more deportation officers."
The state legislature is also in favour of giving permanent residency to the "Dreamers", more than 700,000 undocumented immigrants who were brought into the country as children.
Former president Barack Obama had given Dreamers temporary protection from deportation via the Deferred Action for Childhood Arrivals scheme (DACA), but Mr Trump has vowed to phase it out by March.
A District Court judge in San Francisco infuriated Mr Trump this week when he struck down the President's DACA plan on legal grounds. The President tweeted that the court system was "broken and unfair".
Despite this, Mr Trump has indicated a willingness to provide permanent protection for the Dreamers, but has said he will only support it if the congress legislates for stronger borders and funds the wall.
One of the President's biggest achievements has been to pass sweeping tax cuts through the congress - but the benefits have not been distributed across the 50 states equally.
California has some of the highest state and local tax rates in the country, so its residents relied on being able to deduct those payments from federal income taxes. That provision has been eliminated under the reforms, along with several other tax exemptions.
To counter this disadvantage, Californian politicians have proposed a cheeky workaround that would allow residents essentially to declare their state taxes as a charitable donation - which they could then deduct from their federal income tax liability.
It's a pretty big middle finger to the President.
California this month made headlines when it legalised the sale of recreational marijuana.
The Trump administration pounced quickly, with Attorney-General Jeff Sessions giving prosecutors increased powers to enforce federal laws that make selling cannabis a crime.
The conflict between the state and the federal levels of government has caused confusion - and no doubt harshed the buzz of stoners.
Early this year, Donald Trump opened up the US coasts to offshore drilling.
It's a boon for the resource industry and will no doubt help the President's aim to create more jobs, but environmentalists argue it will be destructive.
Mr de Leon said the change in policy would lead to an assault on the state's "pristine coastline".
Interestingly, the White House has maintained a ban on the politically sensitive drilling off the coast of Florida. So, why is it OK in California but not Florida? Critics say Florida is an exception because it's a battleground state in which Republicans need to retain voter support.
As the Times notes, new laws in California kicked in on January 1 that fly in the face of the President's agenda:
• Allowing parents to withhold a child's gender on birth certificates
• Toughening gun laws to restrict the sales of ammunition and assault weapons
• Stopping ICE officers from rounding up undocumented immigrants in schools, churches, hospitals or courthouses
• Introducing measures to preserve net neutrality
Democratic political consultant Robin Swanson is among the Californians spoiling for a fight. She told Politico: "I think we need to remind the federal government that one in 10 Americans lives here in California, so if they want to pretend that California is an island and push us off as an island of misfits, they're going to be without the economic engine that is California driving it."