Traffic moves across the Brooklyn Bridge, August 2, 2018 in New York City. On Thursday, the Trump administration announced a proposal to weaken fuel-efficiency requirements for the nation's cars and trucks. The rollback is likely to spark legal challenges from California and other states.

A group of 20 U.S. states and several major cities on Friday urged the Trump administration to abandon a proposal to freeze fuel efficiency standards after 2020 and strip California of the ability to impose its own vehicle emissions rules.

The states, including California, New York, Illinois, Massachusetts and Pennsylvania, called the Trump administration proposal "unlawful" and "reckless" in a 143-page document reviewed by Reuters ahead of its filing later Friday. The states have vowed to sue if regulators move forward with the proposal.

Also joining the effort are the District of Columbia, Los Angeles, New York and San Francisco which argue the proposal "would deal a substantial blow in the fight against climate change."

Separately, a group representing major automakers on Friday including General Motors, Toyota Motor and Volkswagen said it urged "the federal government to set achievable future standards that continue to advance environmental and energy goals while recognizing marketplace realities."

Automakers have said they do not back freezing the standards but nearly all have not specified how much they want requirements to rise. They are pressing California and the federal government to retain nationwide emissions rules and avoid a prolonged legal battle.

Honda Motor said Friday it "believes strong standards on the order of 5 percent per year annual improvement paired with policy incentives that support a transition to future vehicle electrification, can provide a balanced solution."

The proposal has set up a major battle between the Trump administration and California over whether the largest U.S. state, which has made reducing greenhouse gas emissions a major priority, will continue to have authority to oversee vehicles.

In separate comments filed Friday, California said the proposal "would worsen air quality for the most vulnerable, waste billions of gallons of gasoline, forfeit our best chance to fight climate change and result in years of uncertainty in the marketplace."

Friday marks the deadline for the filing of comments on the administration's proposal, which details a number of potential alternatives.

The Trump plan's preferred alternative would freeze standards at 2020 levels through 2026 and hike U.S. oil consumption by about 500,000 barrels per day by the 2030s but reduce automakers regulatory costs by more than $300 billion. The proposal would bar California from requiring automakers to sell a rising number of electric vehicles.

California suggested the U.S. Transportation Department and Environmental Protection Agency "contrived the proposal to support the president's impulsive and uninformed direction to 'cancel' the program."

The Obama administration had adopted rules that call for a nearly 5 percent annual increase in fuel efficiency requirements over that period.

The Trump administration argues the new rules will save up to 12,700 motorists lives over the coming decades because they lower the price of new vehicles, prod people into buying safer newer vehicles faster and result in motorists driving less because gas-guzzling vehicles will cost more to operate.

A memo released in August from the EPA said some officials believed the plan would actually increase traffic deaths from 2036 through 2045 because of increasing vehicle travel.