Vehicles make their way westbound on Interstate 80 across the San Francisco-Oakland Bay Bridge as seen from Treasure Island in San Francisco, Dec. 10, 2015. Credit: Ben Margot | AP

The Trump administration and California clean-air officials remain “pretty far apart” in their bid to strike an agreement on automobile fuel economy and greenhouse gas emissions rules as federal regulators race to finalize a key proposal for the auto industry, the U.S. EPA chief said Monday.

“We certainly hope to have a 50-state solution but at the end of the day we have to move forward with regulation,” Environmental Protection Agency Acting Administrator Andrew Wheeler told Bloomberg Television in an interview Monday. “California is an important player — an important part of this — but this is not a two-sided negotiation for a national standard.”

Wheeler planned to meet with California Air Resources Board Chairman Mary Nichols later on Monday to discuss the standards, he said. Wheeler said he would prefer to reach a deal with California, but said the state should not be able to dictate the requirements. The EPA and National Highway Traffic Safety Administration have already proposed stripping California of its authority to set its own tailpipe greenhouse gas emission limits for new cars and trucks, a potent bargaining chip to extract concessions from the largest state for U.S. auto sales.

In the interview, Wheeler said California “should not” have that authority.

“That’s why we would love to have a 50-state solution so we wouldn’t have to pull that trigger,” Wheeler said.

Wheeler’s comments highlight the stalemate between the Trump administration and California officials over fuel economy and tailpipe carbon emissions standards for automobiles, one of former President Barack Obama’s signature policies to ward off climate change.

Wheeler dismissed an earlier counteroffer by California to extend the timeline of the existing requirements, saying it would not lower vehicle prices and improve road safety enough.

The sides have been on a collision course since August, when the EPA and NHTSA proposed capping efficiency standards at a roughly 37-mile-per gallon fleet average from 2020 through 2026 — instead of allowing them to rise to almost 50 miles per gallon by 2025 under the existing rules written by the Obama administration.

Wheeler said the administration must finalize the requirements by early April.

“But we do have some hard deadlines,” he said, adding “and we are pretty far apart.”