As the White House moves to revoke the legal foundation behind most US climate regulations, the Senate environment and public works committee has widened its inquiry into corporate influence on federal climate policy. The panel is now examining whether Ford, the country's second-largest car manufacturer, played a part in encouraging the rollback of long-standing rules.

The investigation began in September, when the committee opened probes into roughly two dozen oil companies, lobbying firms, thinktanks and trade associations over their potential involvement in pushing for the repeal of the 2009 "endangerment finding". That determination allows regulators to curb greenhouse gas emissions by formally recognising their threat to public health and welfare.

Now, Democratic senator Sheldon Whitehouse of Rhode Island, the committee's ranking member, has formally requested information from Ford chief executive Jim Farley, citing remarks made by Trump that appeared to implicate the company.

In a letter sent on Thursday, Whitehouse asked Farley to clarify the president's claims that Ford executives had actively advocated for sweeping changes to environmental regulations designed to protect communities and ecosystems.

The request follows Trump's visit earlier this month to a Ford manufacturing plant in Michigan, where he was overheard praising Farley for repeatedly pressing him to ease green rules. Speaking into a live microphone, the president suggested the CEO regularly contacted him to complain about environmental requirements, though he did not specify which policies were targeted.

Whitehouse said the comments reinforced concerns that industry leaders were working closely with the administration to weaken pollution safeguards. He warned that such coordination risked exposing communities to higher levels of harmful emissions.

Ford has been approached for comment.

At the centre of the controversy is the endangerment finding, a landmark scientific and legal determination that underpins federal limits on heat-trapping pollution from vehicles, power stations and major industrial facilities. EPA administrator Lee Zeldin announced in July that the agency intends to rescind the finding, prompting strong opposition from climate scientists, health professionals and environmental groups.

Whitehouse criticised the proposed reversal, arguing that it would primarily benefit large polluters while shifting the burden onto ordinary Americans through degraded air quality, rising healthcare costs and mounting climate-related economic damage. The finding has previously been upheld twice by the US supreme court.

Ford has publicly supported certain climate initiatives, including commitments to reduce its own emissions and endorsements of the Paris climate agreement. At the same time, the company and its chief executive have resisted several federal climate measures.

Last month, Farley welcomed the administration's decision to weaken vehicle fuel efficiency standards, praising the move as a better alignment with market conditions. Ford has also continued its membership in industry associations that have challenged EPA regulations.

While the repeal of the endangerment finding is expected to move forward, officials have indicated that internal White House reviews could delay final approval.