A “CLOWN” IS what President Donald Trump recently called Gavin Newsom, the current lieutenant-governor and Democratic candidate for governor of California. Mr Newsom responded by comparing Mr Trump to Pennywise, the evil clown from Stephen King’s horror novel, “It”. A personal connection made the spat juicier. Mr Newsom’s ex-wife, a Democrat-turned-Republican, happens to be dating Mr Trump’s eldest son.

California is already at war with the federal government, having sued it 44 times since Mr Trump took office, on issues such as health care, internet policy, immigration and the environment. Under its current governor, Jerry Brown, who is 80, California has proudly nurtured an alternative political vision for America, most notably by adopting aggressive standards to combat climate change at a time when Mr Trump praises coal.

The president has endorsed John Cox, a Republican businessman who has focused on illegal immigration and California’s high costs. But Mr Trump is unpopular in California, and Mr Cox trails Mr Newsom by about 20 percentage points in the polls. So large is Mr Newsom’s lead that, rather than campaigning to win the election, he is already promoting his agenda. This includes boosting investment in early childhood education, embracing immigrants and offering universal health care.

As San Francisco’s mayor from 2004 to 2011, Mr Newsom famously allowed same-sex marriages, defying then-president George W. Bush, who supported a federal ban. He has a track record for avant-garde and creative policymaking. As a supervisor he championed offering services, not cash, to San Francisco’s legions of homeless. Long presumed to have national political aspirations, in 2004 he and his then-wife appeared on the cover of Harper’s Bazaar dressed in black tie, under the headline “The New Kennedys”.

In many ways Mr Newsom is a politician more in the mould of the 1960s than today. He has the look and smoothness of a seasoned politico. Running San Francisco gave him rich experience of urban politics—in some ways the post is more powerful than the mayoralty of Los Angeles. At a time when many ambitious Democrats are pushing to the left and shunning the party establishment, Mr Newsom is frank about his close ties to Nancy Pelosi, the longtime congresswoman from San Francisco and former Speaker of the House.

Governing California is likely to prove much harder than winning the election. Mr Newsom’s ambitions for the office are large and many of his projects, such as offering health care to all Californians including illegal immigrants, will be costly. He will have to balance fiscal prudence with his social conscience. He has not outlined how he intends to pay for new services, and some anticipate he will be more prodigal than his predecessor. Mr Newsom insists that such accusations are “lazy punditry based on pure speculation. I am not profligate any more than Jerry Brown was.”

Another question is what happens when California’s economy, the world’s fifth-largest, falls on harder times, as it will eventually. Mr Newsom points out that he ran San Francisco during a downturn: “I have no experience managing in an abundance. I have experience in managing in scarcity.” California’s economy has boomed for much of the last decade, and Mr Brown convinced Californians to set aside money to cover future budget shortfalls. Yet even a mild recession would wipe out those reserves in a single year, says Gabriel Petek of S & P Global Ratings, a financial-information firm.

Because of a property-tax revolt in the 1970s, California relies heavily on income taxes. And, because it is a progressive state, it squeezes the rich. Just 1% of its people account for 46% of personal-income tax revenues. Tax rates probably cannot rise much higher without driving people away. How California handles its economy and budget under a new governor will be closely watched by many—including by Mr Newsom’s foe in the White House.