LOS ANGELES - The US Environmental Protection Agency (EPA) on Tuesday announced a proposal to rescind a key 2009 climate determination that has served as the legal basis for regulating greenhouse gas emissions from motor vehicles, including mandates supporting electric vehicle (EV) adoption.

EPA Administrator Lee Zeldin unveiled the proposal at an auto dealership in Indiana, stating that the agency seeks to revoke the 2009 Endangerment Finding, which declared greenhouse gas emissions a threat to public health and welfare.

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According to the EPA, the 2009 Endangerment Finding has underpinned more than $1 trillion in regulatory costs.

"If finalized, this proposal would undo the underpinning of $1 trillion in costly regulations, save more than $54 billion annually," the agency said in a statement.

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"With this proposal, the Trump EPA is proposing to end sixteen years of uncertainty for automakers and American consumers," said Zeldin.

If enacted, the proposal would eliminate all existing greenhouse gas standards for light-, medium- and heavy-duty vehicles and heavy-duty engines. These standards, introduced beginning in 2010, include regulatory elements such as off-cycle credits and features like automatic start-stop systems that have drawn criticism from some consumers and industry groups.

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The EPA will open a public comment period to solicit input on the proposal.

The move is expected to draw strong opposition from environmental organizations and lawmakers who view the 2009 Endangerment Finding as a critical element of US climate policy and a necessary mechanism for reducing carbon emissions.