California is suing the federal government over Donald Trump’s on-again-off-again tariffs.

The governor and attorney general claim the American president does not have the right to impose them.

The move marks the strongest pushback yet against a tariff roll-out that has sent global stock markets into meltdown, and left businesses across the US fretting about uncertainty.

It’s the worst own-goal in the history of this country,” California Governor Gavin Newsom said. “One of the most self-destructive things that we’ve experienced in modern American history.”

With 40 million people and a large, outward-facing economy that accounts for 14 percent of US GDP, California looks set to bear the brunt of the economic damage forecasters expect from recent gyrations.

Newsom’s office says California which would be the world’s fifth-largest economy if it were an independent country could lose billions of dollars in revenue if Trump’s tariff policies shrink international trade.

Trump has long prized tariffs as a tool to achieve what he says is the urgent task of rebalancing America’s trading relationships, and pledged on the campaign trail that he would hit imports with extra levies.

Initial punitive tariffs against Mexico and Canada were built on with his self-declared “Liberation Day,” which saw onerous charges imposed on scores of countries, including allies and partners.

Many of those duties have since been paused, but their chaotic announcement sent global stock markets into spasms, wiping out trillions of dollars of value.

Newsom said Trump’s economic mismanagement was costing everyday Americans — including many who voted for Trump — dearly, all while feathering the nests of billionaire donors and friends.