Washington (CNN) It's the most populous state in the country and the US President hasn't been there since he took office.

His presence probably hasn't been missed; his approval rating in California is below 30%, among the lowest in the country, according a recent Gallup survey . When he goes to San Diego this month, it'll be to view prototypes for a border wall that faces steep opposition in the state. Take that!

President Donald Trump and his administration have very much tied his political efforts to California by essentially declaring a policy war on the Golden State. On immigration, legalized marijuana, climate change and more, California is the chief policy foil of the White House.

The latest exhibit came Tuesday night with news that the Trump administration would sue the Golden State over state laws that seek to shield the undocumented from federal immigration authorities -- so-called "sanctuary state" laws.

Attorney General Jeff Sessions said he was doing it all to help public safety. California Gov. Jerry Brown called Sessions' press conference in Sacramento a "stunt."

It's a legal fight that's sure to play itself out over the coming years. It's also not even close to the only effort the administration has undertaken against California immigration policies.

The Justice Department is also withholding some federal funds from the state because of the laws -- a move a federal judge allowed Monday to continue while he hears a separate lawsuit.

Another judge in California recently ruled for the administration in a separate suit , this one brought by California, which tried to block construction of a border wall because of environmental regulations.

Trump's ongoing effort to end the DACA program, which shields some children undocumented immigrants from deportation, adversely affects California, which has the largest number of DACA recipients.

State officials seem to welcome the ongoing legal fight. The Sacramento Bee cataloged 17 different lawsuits filed by California against the Trump administration in 2017. And they weren't just on immigration. Birth control, student loans, energy use in appliances. The list goes on

But there are more urgent and immediate differences as well. But the divisions are more urgent than policy lawsuits.

The Oakland Mayor, Libby Schaaf, issued a public warning to the undocumented immigrants in Oakland that ICE was preparing an operation in Northern California.

"I am sharing this information publicly not to panic our residents but to protect them," she said in a February 24 release.

ICE Deputy Director Thomas Homan said the warning had the opposite effect, because more than 800 immigrants with criminal records were at large in the community.

Sessions was more direct on Wednesday.

"How dare you needlessly endanger the lives of law enforcement just to promote your radical open borders agenda," he said of Schaaf.

After the sanctuary laws were enacted in January, Homan had seemed to threaten California to "hold on tight" for federal scrutiny and promised more deportations.

The federal dispute with California over undocumented immigrants is the most immediate and urgent dispute, but there are others.

California is among the coastal states fighting the administration's plan to selectively increase offshore oil drilling. (Florida, so far, has been exempted.)

Meanwhile, Brown has made himself a chief Trump critic on climate change, taking the alarm of federal government inaction to the international stage and promising California, which has its own Environmental Protection Agency, would try to step into the void.

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The state and federal government are also at odds over fuel economy standards for cars and trucks.

Shortly after California officially legalized marijuana for recreational use, Sessions rescinded three Obama-era memos that had made federal authorities laissez faire on such laws.

A lot of this might be natural differences of opinion between a President who was put in office by a coalition of states that did not touch the West Coast. And it's one of the most diverse US states at a time when Trump's core of support is based in white voters

But California is a state that's larger and has a bigger economy than most other countries and where the GOP barely registers as a statewide force -- the state's primary laws mean many ballots could see Democrats vying against other Democrats on Election Day.

And the tension between states and the federal government is certainly noting new; Texas played a leading role opposing the policies of former President Barack Obama.

But the squaring off in this new immigration lawsuit feels different, as did Sessions' rhetoric Wednesday in announcing the suit.

The policy war between Trump and California (and vice versa) is not going to die down anytime soon.