The 70-year-old lawmaker said he had come to Belem, Brazil, to underline that Trump's aggressively pro-fossil-fuel policies do "not represent the American people" -- and that the United States is forfeiting a vast economic opportunity.

"Right now, we are deliberately losing our competition on solar, on wind, on battery storage, on electric vehicles and all the support technologies that go into that," he said in an interview.

"It is a huge self-administered blow that Trump is doing, entirely to pay back his fossil fuel donors."

Whitehouse said that as he arrived in the Amazonian city in the early hours of the morning, he passed numerous Chinese electric vehicle dealerships -- a sight that hammered home his message about America falling behind.

The Trump administration declined to send an official delegation to the COP30 summit, leaving only a few prominent Democrats to attend in an unofficial capacity, including California Governor and presumed 2028 presidential-candidate Gavin Newsom.

"The Trump administration does not represent the American people on climate," said the Rhode Island senator, known for his long-running "Time to Wake Up" speeches on global warming in Congress.

"They are doing political work for the fossil fuel industry and the public very much supports climate action," he continued, citing a slew of polls to back his point.

For Whitehouse, one of the few remaining pathways to climate safety lies in carbon pricing, which he argued is essential to spark the innovation needed to slash emissions.

"If it's free to pollute, there's really no pathway to safety," he said, reiterating his support for Europe's carbon border tax -- a key point of contention with developing countries at COP30.

Trump, who received hundreds of millions of dollars from oil and gas giants during his presidential campaign, pulled the US out of the Paris climate agreement for a second time on the day he returned to office.

Trump and Republican lawmakers have rolled back clean-energy tax credits and scrapped incentives for electric vehicles, prompting General Motors to scale back production.

Whitehouse's team said he will meet with "heads of state, lawmakers, private sector leaders, environmental champions, and civil society leaders" during his visit.

But he cannot take part in negotiations on the COP's outcome.

Attending the conference itself was made more complicated by resistance from the State Department, he said, which forced him to get his badge through a nonprofit organization.

"I've never seen the State Department be completely unwilling to support members of Congress traveling on an official Congressional Delegation, even to the point of refusing to help us get badges."