WASHINGTON — The Trump administration is expected to start rolling back tough limits on carbon pollution from cars and trucks this week, and may be considering a plan to revoke California’s authority to set its own pollution standards for vehicles, a linchpin of the state’s effort to battle climate change.

Environmental Protection Agency chief Scott Pruitt is pushing the move to weaken emissions standards, siding with auto manufacturers that argue vehicle fuel efficiency standards put in place by the Obama administration will cost billions of dollars. On Thursday, he said he would move “very, very soon” to roll them back.

If that happens, California will probably exercise its special authority, known as a waiver, to keep the current vehicle emissions standards in place, laying the groundwork for an extraordinary tug-of-war between the state and the federal EPA.

Because of the state’s formidable market power, the waiver threatens to undermine the Trump administration’s plan.

The state must cut tailpipe emissions as part of its ambitious plan to slash overall greenhouse gas emissions by 40 percent from 1990 levels over the next 13 years. Transportation is the largest source of carbon pollution in California and the nation, exceeding emissions from power plants. The sector accounts for 36 percent of the state’s greenhouse gas pollution.

“If you look at what California has done to control greenhouse gas emissions, the tailpipe rule has done the largest amount of work,” said Michael Wara, a Stanford University professor of environmental law. “So California is going to fight, to deploy every resource it has, to keep this stuff, because this is big.”

Although Pruitt has not publicly discussed California’s waiver, industry sources say it has been under intense scrutiny.

California’s ability to write its own tighter tailpipe standards was explicitly written into the federal Clean Air Act five decades ago to help the state combat smog in the Los Angeles Basin. Over the past decade, state officials worked with the Obama administration in an aggressive effort to fight climate change by squeezing emissions from gasoline-fired vehicles and begin a paradigm shift toward electric cars and other zero-emission vehicles.

Sen. Ed Markey, D-Mass., promising to fight the administration, called the vehicle tailpipe rules the “single largest step America has ever taken to reduce carbon pollution.”

But Pruitt said last week that he does not believe carbon pollution causes global warming. Ever since his confirmation hearing in January, when he refused to defend California’s waiver under questioning by Sen. Kamala Harris, D-Calif., Pruitt has been expected to attack California’s tailpipe standards, given the hurdle they pose to loosening standards nationally.

Doing so could slash development of low-emission cars by Detroit automakers, setting back by decades U.S. efforts to cut carbon pollution.

Like two heavyweight boxers circling each other, the Trump administration and California appear to be holding back on an immediate confrontation, industry insiders said. The EPA and the California Air Resources Board, which administers the state rules, both declined comment.

The Obama administration developed the current standards as part of the 2009 bailout of General Motors and Chrysler. In return for their rescue by U.S. taxpayers, Detroit automakers agreed to slash greenhouse gas emissions from their cars and light trucks, including a plan to require vehicles sold in model years 2022 to 2025 to achieve a fleet average of 54.5 miles per gallon.

California agreed to follow the new rule so that automakers could meet a single national standard.

In November, after President Trump won the election, the Obama administration moved more than a year ahead of schedule to make the rule final, saying the standard is achievable, and would save consumers $1,650 over the life of each car and the nation 1.2 billion barrels of oil.

Detroit automakers cried foul, accusing the agency of rushing the rule without adequate consultation. The automakers told Trump that it would destroy more than a million jobs, essentially wiping out the industry, despite the rapid progress they’d made to reduce emissions as they geared up to meet the new target.

The Alliance of Automobile Manufacturers wrote Pruitt last month, arguing that “no conventional vehicle today meets that target,” and that electric vehicles that could help them comply comprise only 3.5 percent of new sales. Asked by The Chronicle for elaboration, the group declined further comment.

What changed since the 2009 bailout, aside from administrations, were gas prices, which have fallen sharply since peaking two years ago. Consumers have begun to gravitate back to the sport utility vehicles and pickup trucks that fuel Detroit profits.

If Pruitt blocks the new rule, California will have to use its waiver to continue to demand lower emissions on cars sold in the state. The state Air Resources Board will meet Friday to approve the targets.

More than a dozen other states follow California’s standard, as the waiver allows. Together these comprise roughly a third of the U.S. auto market, dramatically raising the stakes for both sides.

California’s legal authority is well established. No administration has ever tried to revoke an existing California waiver. Doing so would require a new rule-making process that could take years and stands a high risk of failure, legal scholars said.

A decade ago, the Bush administration denied a waiver for the state to expand tailpipe limits to cover greenhouse emissions, but the state sued and the case was dropped by the Obama administration before a court could resolve it.

Trying to revoke the waiver “could be a pretty risky move for auto manufacturers and the administration,” said Ann Carlson, a professor of environmental law at UCLA. “If the administration loses on this, California’s power is then absolutely clear, and it can use that power to issue standards that are stronger, and it can get other states to join in.”

At the same time, California is expected to resist toughening the new tailpipe standards further, even though the state is falling behind in its effort to get 4.5 million zero-emission vehicles on the road by 2030.

Industry sources speculated that state officials may be holding back for fear of provoking Pruitt into attacking the waiver. But in January, after California Air Resources Board Chair Mary Nichols visited the Detroit Auto Show, where electric cars from all the automakers were on display, she issued a statement saying, “The conclusion is inescapable: California’s vehicle future is electric.”

Carolyn Lochhead is The San Francisco Chronicle’s Washington correspondent. Email: clochhead@sfchronicle.com Twitter: @carolynlochhead