In a televised address on Tuesday night, California Governor Gavin Newsom accused President Donald Trump of a "brazen abuse of power".

The Trump administration's immigration enforcement efforts were terrorising his state's immigrant neighbourhoods, he said.

"California may be first, but it clearly will not end here," he warned. "Democracy is under assault before our eyes."

Newsom's speech was the latest salvo between the US president and the Democrat who heads America's most populous state.

The clash between the two leaders presents a formidable challenge to the 57-year-old governor.

But it also offers a political opportunity for a man whose term in office ends next year and has his own presidential ambitions.

"This is unquestionably an opportunity for Gavin Newsom," said Darry Sragow, a long-time California Democratic strategist.

He adds, however, that as the state's governor, Newsom has an obligation to defend California - whether it's in his political interests or not.

"It's a call to duty," he said.

Trump has accused Newsom of being "grossly incompetent" and of failing to adequately respond as some of the Los Angeles protests turned violent.

He's dusted off an earlier derisive nickname for the governor, "Newscum", and said on Tuesday that he believed arresting him would be a "great thing".

According to media reports, the White House is considering whether to cut off federal aid to California, including billions of dollars of education grants.

"Gavin Newsom's feckless leadership is directly responsible for the lawless riots and violent attacks on law enforcement in Los Angeles," White House deputy press secretary Abigail Jackson said in a statement.

"Instead of writing fundraising emails meant to score political points with his left-wing base, Newsom should focus on protecting Americans by restoring law and order to his state."

Newsom called the arrest threat a step toward authoritarianism and said Trump's deployment of military personnel to secure federal buildings and protect immigration officials had inflamed protests that had been isolated and controlled.

"The rule of law has increasingly given way to the rule of Don," he said in his Tuesday night address.

Over the past few days, Newsom has become the face of a Democratic Party that has often struggled to present a clear and unified alternative to Trump's Republican administration on the national stage.

The governor's set-piece speech, delivered in a suit while standing in front of California and US flags, received widespread press coverage and attracted well over a million views on assorted YouTube channels.

Newsom's press team has also been active on social media, comparing Trump to the evil Emperor Palpatine from the Star Wars films.

According to the Washington Post, the TikTok followers on his official governor's account have doubled to 897,000 in the past few days.

"There is a very real possibility that Newsom will come out of this with a significant and favourable national profile," Sragow said.

He says that the more Newsom can outline a story of Trump against California - a state with whom the president has a very clear grudge - the better the chances for the governor to benefit.

"Don't make this into a mano-a-mano shootout between two gunslingers on the streets of Laredo," he said.

Trump and Newsom have always presented a contrast in stories and styles – the brash outer-borough New Yorker versus the polished San Francisco cosmopolitan.

Newsom was elected to office in 2018, in the Democratic mid-term wave election that marked the first major voter pushback against Trump's first presidential term.

He promised to make his state a counterpoint to Trump's national right-wing populism, but his political journey hasn't always been a smooth one.

He flirted with controversy during the Covid pandemic, as he backed aggressive lockdowns of public spaces – but gathered for a birthday celebration at a posh French restaurant in November 2020.

His political opponents, sensing weakness, triggered a recall election in September 2021 – but Newsom won the vote by a comfortable margin.

Newsom won re-election to a second four-year term in 2022 and became more involved in national Democratic politics, fuelling speculation that he harboured presidential ambitions.

He became a high-profile surrogate for Joe Biden's re-election campaign and took to Fox News for high-profile debates with Florida Governor Ron DeSantis, who was at the time running for the Republican presidential nomination, in December 2023.

After Trump's re-election last November, Newsom made a noticeable tack to the political centre.

He expressed new discomfort with transgender athletes in women's sports, called for curtailing health benefits for undocumented workers, and hosted conservative guests like former White House senior adviser Steve Bannon on his political podcast – provoking the ire of some in the Democratic Party.

In January, he toured the devastating fire damage in a Los Angeles suburb with Trump and pledged to work with the new Republican administration in recovery efforts.

The Los Angeles protests have brought a sudden and decisive end to that detente, as the two men square off across a deep political divide.

Trump has frequently benefitted from having a political foil with which to contrast himself – whether it was Hillary Clinton in 2016, Nancy Pelosi in the latter years of his first presidential term or Joe Biden during his drive back to power.

While there are risks for Newsom in this fight – suspension of federal aid to California and the threat of arrest being just two notable ones – it is also a clash he seems more than willing to embrace. (BBC)