Gov. Jerry Brown and legislative Democrats announced Wednesday that they are scaling back their ambitious proposal to address climate change by dropping a mandate that the state cut petroleum use by 50 percent amid ongoing opposition from the oil industry and some lawmakers.

Brown and Senate President Pro Tem Kevin de Leon, a Los Angeles Democrat, had pushed a far-reaching proposal to cut petroleum use by half, boost renewable-electricity use to 50 percent and double energy efficiency in existing buildings. De Leon announced Wednesday that he was dropping the mandate to cut oil use from his proposal, SB350.

With just two full days remaining for bills to emerge from the current legislative session, a massive lobbying campaign from oil interests could not be overcome, de Leon said. "We couldn't cut through the multibillion-dollar smoke screen created by big oil with a bottomless war chest," he said.

The Democratic governor has made climate change the centerpiece of his final term. He said Wednesday that lawmakers "did not cave in" to calls to scale back state authority to set emission rules and vowed to continue pushing for the 50 percent oil reduction through the regulatory process.

"The only thing different is my zeal has been intensified to a maximum degree and nothing, nothing is going to stop this state from pushing forward" on aggressive climate change standards, he said.

Brown said the primary sticking points for moderate Democrats in the state Assembly concerned the California Air Resources Board, an unelected body with broad power to set vehicle emissions and fuel standards to decide how the state will reduce oil use.

The governor said opponents agreed to pass the legislation if he agreed to dramatically scale back its power, but he refused.

The legislation has faced intense lobbying on both sides in recent weeks.

Many Assembly Democrats — including moderates and those representing less wealthy districts — expressed concerns that the proposal would hurt California's economy and working-class residents. They sought greater oversight of the air board that has been in charge of implementing California's ambitious greenhouse-gas emissions law signed by Gov. Arnold Schwarzenegger.

Sen. Bob Huff, R-San Dimas, who until recently was the Senate minority leader, said the announcement was "a step in the right direction."

"I think that was the most problematic component of SB350 because it hit everybody in ways we don't even know, how technologically we were going to accomplish the goal," Huff said in an interview.

He said he needs to understand the costs associated with the remaining portion of the bill before he can support it.

Brown has campaigned on climate change this year, discussing it with the pope at the Vatican in July, and is expected to attend the United Nations climate change conference in Paris in November.

He said the intense debate surrounding the legislation may have actually helped the cause of climate-change legislation in the long term.

This story has been updated.