WASHINGTON — President Trump has never been one to dive into the details of policy, especially now, as an impeachment inquiry threatens to engulf his administration. In recent days, he has allowed his son-in-law to lead a major policy shift in the Middle East and has backed away from a high-profile promise to ban flavored e-cigarettes.
But even as his presidency teeters, one of the few policy issues that has maintained Mr. Trump’s personal focus is not one central to his political appeal, like immigration or trade.
It is the state of California.
The state has been a political fixation since the early days of his presidency, but that was heightened this autumn. Mr. Trump has attended meetings, asked detailed questions at briefings and pressed aides to find ways to use policies to go after the most populous state in the union, according to three people familiar with the matter. Aides say that Mr. Trump remains deeply involved on immigration policy, like a recent decision to slash the nation’s refugee program nearly in half, and on trade. But they describe him as obsessed with narrow policies that directly affect California. Beyond those three policy matters, little else has penetrated the swirl of impeachment.
Two Californians, Speaker Nancy Pelosi and Adam B. Schiff, chairman of the House Intelligence Committee, are leading the impeachment investigation. The state’s Democratic governor, Gavin Newsom, has been unsparing in his criticism and his legal challenges.
And the president’s response appears to be personal. Beyond the name-calling — “Shifty” Adam Schiff and “Nervous Nancy” Pelosi — he has held California Democrats responsible even for the state’s natural disasters.
“The Governor of California, Gavin Newsom, has done a terrible job of forest management,” Mr. Trump wrote on Twitter this month, adding a threat: “Every year, as the fire’s rage & California burns, it is the same thing — and then he comes to the Federal Government for $$$ help. No more. Get your act together Governor.”
Governor Newsom’s ex-wife, Kimberly Guilfoyle, now a Trump campaign adviser and girlfriend of Donald Trump Jr., has joined in the criticism on Twitter and at campaign events. And the House Republican leader, Kevin McCarthy of California, has often counseled Mr. Trump on the politics of his state.
In a statement, a White House spokesman, Judd Deere, said, “California leaders continue to support destructive liberal policies that kill jobs, increase housing costs, provide sanctuary to criminal illegal aliens, and ignore longtime environmental issues.”
Since the beginning of his presidency, Mr. Trump has been enthusiastic about his administration’s push to roll back Obama-era rules on climate-warming auto pollution, framing it as a signature move to save an iconic industry from burdensome red tape. For most of that earlier period, Mr. Trump stayed away from the complex regulatory details involved in undoing the regulation, according to two current and two former White House officials.
That changed with Governor Newsom’s deal with the automakers. Suddenly Mr. Trump was delving into policy details.
The administration and Justice Department have pushed an unusual series of legal and policy moves against California and the auto companies that backed the state’s climate change plan.
Last month, the Justice Department filed suit to force the state to drop Quebec from its central effort to limit greenhouse gases from power plants, arguing that a state could not conduct foreign policy. In September, the Environmental Protection Agency threatened to withhold federal highway funding from California if it did not address a decades-long backlog of air pollution control plans.
Also in September, the administration opened an antitrust investigation into the four automakers that sided with California over Mr. Trump in the dispute over fuel efficiency standards.
When aides told Mr. Trump that the final details of his rollback of the auto emissions rule would most likely not be completed before the end of this year, he demanded faster action. Officials at the E.P.A. and the Department of Transportation responded by separating out California’s portion of the rule and releasing it in September.
Mr. Trump announced the new rule on Twitter while in Los Angeles for a fund-raiser.
That night, Mr. Trump told reporters aboard Air Force One that his administration would issue a notice of environmental violation against the city of San Francisco because of its homelessness problem.
On Twitter and in speeches, Mr. Trump has frequently seemed to find ways to disparage his West Coast target. In a Nov. 12 appearance at the Economic Club of New York, Mr. Trump responded to a broad question about climate change with a detour into California: “Los Angeles? What a — what a mess that is.”
Barry Rabe, a public policy professor at the University of Michigan who is writing a book about the history of the state-federal relationship, said there were no historical parallels for the president’s obsession.
“I cannot think of another president who sustained a political jihad against a specific state,” he said.
Professor Rabe expressed particular surprise about the administration’s Oct. 23 lawsuit to block California’s climate change program with Quebec, since that relationship has been in place for a decade.
“This is a pretty established policy,” he said. “It’s never had a serious legal challenge, and it’s not like it’s something the Trump administration came in with a plan to pursue.”
“This is like going out of your way to find something to bring against the state,” Professor Rabe added.
If anything, the president’s attacks on California have helped his fund-raising from Republicans in the state. On a visit in September, Mr. Trump raised around $15 million for his re-election effort, according to Republican officials.
“This is great support from a lot of people who have financially contributed to the campaign,” Tim Murtaugh, the Trump campaign’s communications director, said.
Xavier Becerra, the California attorney general, said he was undeterred by the president’s personal attention. The state has already filed over 60 lawsuits against the Trump administration — more than any other filed by a single state against any administration, according to Paul Nolette, a political scientist at Marquette University who maintains an online database of state litigation and activity by attorneys general. (The runner-up is Texas, which has sued the Obama administration 48 times over eight years.)
Last week, Mr. Becerra’s office filed its second lawsuit to block the administration’s effort to revoke California’s authority to regulate tailpipe emissions.
“He’s a bump in the road of what we’re trying to do,” Mr. Becerra said. “So I’m just figuring out, do I go over the bump or around the bump?”
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