Battle lines between liberal politicians and the president intensified this week as Trump’s administration targeted cannabis, immigrants and the environment

In the first hours of 2018, Californians toasted with “Happy New Year blunts” and marijuana gummies, celebrating the launch of the largest legal pot market in the world.

Three days later, Donald Trump’s administration announced a policy that could allow US prosecutors to target legal marijuana operations and undermine California’s massive cannabis movement.

“There should be no doubt that President Trump has officially declared war on California,” state senate leader Kevin de León told the Guardian on Thursday after the US attorney general, Jeff Sessions, rescinded an Obama-era policy that opened the door for states to legalize marijuana.

Play Video 2:19 California's marijuana muddle – video explainer

The federal government’s war on the Golden State – which overwhelmingly rejected the president in 2016 and has become a liberal leader in the anti-Trump resistance – has intensified in recent days with the administration threatening California’s immigrants, world-famous coastal shores, taxpayers and weed smokers.

We are not going to tolerate it. We are going to fight back Barbara Lee, California congresswoman

The political warfare by Trump, who reportedly holds deep grudges and is said to be obsessed with his electoral wins and losses, has the potential to cause havoc and destroy livelihoods in the state of California, the world’s sixth largest economy.

“These are bullying tactics of the Trump administration,” said Barbara Lee, a congresswoman in northern California who has protested against the president since his inauguration. “We are not going to tolerate it. We are going to fight back.”

To some progressive leaders, the most terrifying threat this week came on Tuesday when Immigration and Customs Enforcement (Ice) promised to “significantly increase” the number of deportation officers in the state in direct response to California’s new “sanctuary state” law, which is meant to limit local police cooperation with Ice and protect immigrants.

“California better hold on tight,” acting director Thomas Homan told Fox News, later suggesting that sanctuary jurisdictions are breaking federal laws. Some interpreted his comments as an outrageous threat to arrest and prosecute Democratic politicians.

Saira Hussain, an attorney with Asian Americans Advancing Justice, which recently challenged Ice over its ongoing raids against Cambodian Americans in California, said: “It’s really alarming to see such an authoritarian streak coming from this administration.”

Of the potential prosecution of officials, she added, “It’s just such a gross violation of the constitution.”

In September, the Trump administration boasted about targeted raids in sanctuary cities, drawing widespread criticisms that Ice was ripping apart families with a retaliatory program. A larger-scale enforcement effort could be devastating in California, which is home to more than two million undocumented people.

Facebook Twitter Pinterest A sales clerk with cannabis plants at a cannabis dispensary in Oakland, California. It became legal to buy recreational cannabis on 1 January. Photograph: John G. Mabanglo/EPA

Ice declined to comment on whether it plans to prosecute politicians, but an official said in an email, “Ice and DoJ [the Department of Justice] are working collaboratively to explore any and all potential options for holding sanctuary jurisdictions accountable for their dangerous practices.”

The threat alone spreads the false narrative that undocumented people are dangerous, Hussain added: “When there is talk about deporting whole swaths of our communities, it does create massive amounts of fears.”

Sessions’ threat of a cannabis crackdown dampened the festive mood in California, where the new law allows for retail shops and makes it legal for adults to possess and grow pot. The policy shift by Sessions – who once said he admired the KKK until he found out they smoked marijuana – would give US attorneys, who are appointed by the president, discretion to enforce federal marijuana prohibition laws.

“They don’t have the ability to stop legalization, but they do have the ability to hurt a lot of people in the process,” said Tamar Todd, legal affairs director of the Drug Policy Alliance, which helped pass California’s law.

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Some view California legalization as the point of no return for national reform, which may be motivating Sessions, Todd said.

De León, who is running for US Senate, said the move seemed political: “This is Jeff Sessions trying to impose his 1950s worldview on the people of California.”

Lee, noting that marijuana laws disproportionately targeted black Americans and fueled mass incarceration, added: “Jeff Sessions really is a poster boy for institutional racism.”

On Thursday, the Trump administration also announced a plan that would open almost all US offshore territory to oil and gas drilling, including the coastal waters of California, sparking further backlash from leaders on the west coast.

Trump’s tax bill is also on track to hurt California residents due to a change in property tax law that is detrimental to states with high taxes and costs of living.

Keith Kolb, a 57-year-old San Francisco resident, said a Trump war on California weed would further unite angry voters.

“It has brought a lot of people together to fight against this administration,” said Kolb, adding that other states will support legalization once they see the tax revenues. “The rest of the country will follow and say we want some of that.”