Lobbyists and energy experts said the White House’s expected announcement of a more stringent vehicle fuel economy standard boosts momentum for climate change legislation being marked up in the House this week.

“With the White House and Congress moving this week, the different tracks going at the same time creates the notion that there’s a lot going on — which there is,” said Frank Maisano, an energy industry lobbyist. “They wanted in the first half of the year to send a strong message about the direction they wanted to go, and that’s what they are doing.”

The White House is expected to announce Tuesday an agreement among the federal government, California and the auto industry to set a nationwide standard for fuel economy based on California standards.

The state had been pressing for a waiver from the Clean Air Act (PL 101-549) that would allow it to enforce tougher standards than the federal government’s.

The agreement would require automakers to meet an average fleetwide fuel economy standard of 35.5 miles a gallon by 2016, accelerating the timetable for federal standards set in a 2007 energy law (PL 110-140), which would have required that standard to be met by 2020. The current standard is 27.5 miles per gallon.

A senior White House official said the move is projected to save 1.8 billion barrels of oil and prevent the emission of 900 million metric tons of greenhouse gases. The official said the regulations would add about $600 to the cost of new cars, but the increase would be offset by consumer savings on gasoline.

“These are historic regulations. They are the toughest-ever fuel efficiency and first-ever greenhouse gas standards,” the official said.

Democrats who are trying to advance a bill that would cap greenhouse gas emissions hailed the move. The House Energy and Commerce Committee is marking up the bill (HR 2454) this week.

Rep. Lois Capps , D-Calif., an Energy and Commerce member, called the expected White House announcement “great news.” The agreement “confronts our nation’s addiction to oil head-on, marking the first time the U.S. will have adopted a national standard for greenhouse gas emissions,” she said.

The agreement follows months of negotiations among the auto industry, the EPA, the White House Council on Environmental Quality, and the National Highway Traffic Safety Administration. The agreement will not actually grant California’s request for a waiver, “but by making California’s standard the national standard, it moots the request for the waiver,” said Daniel J. Weiss, a climate policy expert with the Center for American Progress, a liberal think tank.

Automakers Express Support

Several major automakers, including General Motors Corp., have endorsed the plan.

“It will establish a single national standard that will provide predictability and certainty for the auto companies in meeting regulations, which the industry apparently believes it can achieve over a realistic time frame,” said Sen. Carl Levin , D-Mich., an ally of the industry.