California Governor Gavin Newsom speaks at a press conference, accompanied by members of the Texas Democratic legislators, at the governor’s mansion in Sacramento, California, U.S., August 8, 2025. REUTERS/Carlos Barria

By Valerie Volcovici

BELEM, Brazil (Reuters) -California Governor Gavin Newsom has arrived in the Amazon city of Belem with a message for the COP30 summit: his state will continue to be a "reliable partner" on climate policy and green technology despite Washington's abandonment of the effort.

A strident political foe of U.S. President Donald Trump, Newsom has for months been teasing a run for the White House in 2028. On Tuesday and Wednesday, he is expected to meet with officials from some of the 195 governments attending this year's U.N. climate negotiations.

He has planned meetings with a series of subnational leaders, including the governor of Brazil's state of Para, the location of the summit.

Though California is just one of 50 U.S. states, its economy is the world's fourth-largest - making it a key player in influencing markets and energy policy.

"The reason I'm here is in the absence of leadership coming from the United States," he said at an investors summit in Brazil's financial hub of Sao Paulo on Monday. "This vacuum, it's rather jaw-dropping."

Newsom has touted California's embrace of green tech, highlighting that the state has seven times more renewable energy jobs than fossil fuel jobs and reminding people that EV giant Tesla was founded in California. This is in sharp contrast to Washington's climate denial and determination to boost global use of polluting fossil fuels.

Newsom also lamented the U.S. rollback on clean energy policy as ceding the fast-growing green-tech market to China.

"China gets it," Newsom told investors. "United States is toast competitively if we don't wake up to what the hell they're doing in this space, on supply chains, how they're dominating manufacturing, how they’re flooding the zone here, EU, elsewhere, Africa."

China not only dominates the markets for electric vehicles, renewable energy components and batteries, he said, but it also leads in software while U.S. automakers like General Motors are "trying to recreate the 19th century," Newsom said. GM recently slowed its production of EVs.

The United States has conspicuously snubbed this year's COP30 summit, with Trump falsely declaring climate change a hoax.

Some diplomats worried that Trump's Republican administration might try to disrupt the summit from afar.

Newsom, a Democrat, said last month that he is mulling a presidential run in 2028. He has started to parrot Trump's brash style of messaging on social media.

Last week, California voters backed his proposal to redraw the state's voting districts to offset redistricting in other states aimed at boosting the number of congressional seats held by Republicans.

Newsom told investors in Sao Paulo that Trump was emulating Russia and Saudi Arabia in turning the United States into a "petro state" and embracing Chinese-style "state capitalism" over the free market. He criticized Trump's aggressive tariff policies as "madness from an investment perspective."

"I feel like it's modeled a little bit on President Xi, not President Reagan. The hell's going on?" he said.

(Reporting by Valerie Volcovici in Belem, Brazil; Editing by Katy Daigle and Matthew Lewis)