The rollback of the Obama administration’s fuel efficiency standards for automobiles took another step forward Thursday when the Transportation Department’s National Highway Traffic Safety Administration sent a proposal to the Office of Management and Budget.

The OMB did not release the contents of the document but is expected to publish it by the end of June, prompting a 60-day public-comment period.

The draft of the overhauled standard, as reported last month, would eliminate automakers’ obligation to boost fuel efficiency after 2021 and would set up a clash with California by challenging its ability to set its own stricter standards, a power granted to the state by the Clean Air Act.

Mary D. Nichols, head of the California Air Resources Board, met in Washington with officials from the Transportation Department and the Environmental Protection Agency in an effort to alter the Trump administration’s position. The EPA and Transportation issued a news release afterward calling the conversations “productive” and saying that they were “fully supportive of an open dialogue that proceeds in an expedited manner.”

Then on May 24, Nichols tweeted: “Sounds like a great meeting based on the WH press release. Too bad it’s not the one we attended.”

She said she was quoting and elaborating on what President Trump said about canceling his planned summit with North Korean leader Kim Jong Un: “If and when (@ & @) choose to engage in constructive dialogue and actions, I am ready.”

California Attorney General Xavier Becerra issued a statement Thursday saying, “We don’t intend 2018 to be any different because for California, taming greenhouse gas emissions isn’t a choice, it’s a necessity.”

The fuel efficiency standards were negotiated with automakers by President Barack Obama’s administration in 2011. The standards would double average fleetwide fuel efficiency to about 50 miles per gallon by 2025. The agreement was both a major climate policy and a national security matter. It cut greenhouse gas emissions of automobiles by reducing gasoline burned and lessened U.S. dependence on petroleum imports by cutting use by about 2 million barrels a day.

Dan Becker, director of the Safe Climate Campaign, said that once the OMB begins the comment period and makes the proposal public, “then let the lawsuits begin.”