For two years, Sacramento Sen. Darrell Steinberg coaxed builders, environmentalists and housing advocates into agreement on an ambitious plan to cut global warming pollutants in California.

Now, he needs one more signature to make it law, and he's got two more days to get it. But that would-be signer, Gov. Arnold Schwarzenegger, is balking.

The deadline is Tuesday.

Senate Bill 375 directs the state Air Resources Board to set greenhouse gas reduction targets for each of the state's 17 regional areas, including Sacramento. It offers incentives for cities and builders that turn growth inward, away from sprawling suburbs.

It's inspired by the Sacramento region's recent Blueprint to reduce car commutes with more urban-style housing and more transit.

Proponents call it far-reaching. Opponents say it overreaches.

Schwarzenegger administration officials reportedly fear the bill could thwart billions of dollars of already planned major road projects in the state, such as carpool lanes on freeways.

In a Friday meeting with administration officials, Steinberg, the state Senate's president pro tem-elect, disagreed, but promised to clear that up with further legislation, if need be.

He pointed out the bill will fast-forward Schwarzenegger's oft-stated desire of leading the world in reducing greenhouse gases, blamed for global warming.

"This is not just another bill," Steinberg said Saturday. If the governor vetoes it, Steinberg warned it would be very hard to resuscitate next year. "The coalition is a fragile one."

Administration officials declined to comment Saturday.

In a Friday speech, however, Schwarzenegger voiced reservations.

"It will be a huge bill," Schwarzenegger acknowledged, a follow-up to landmark AB 32 two years ago, requiring California to reduce greenhouse gas emissions dramatically by 2020. "The important thing is, again, that it is written the right way. I'm going to look at that bill very carefully, because in principle, I love that idea."

If the bill becomes law, proponents say the next generation of Californians will drive less and live closer to work and closer to each other.

Call it California Condensed.

The plan instructs metropolitan areas to put a belt around growth plans and cinch it up a notch or two.

Sacramento transportation official Mike McKeever said the bill could put California at a historic tipping point – when it starts making as much financial and social sense to build inward as outward.

"It's a way new era," said McKeever, Sacramento Area Council of Governments chief.

But state Sen. Tom McClintock, R-Thousand Oaks, has called it a case of "authoritarians on the left" telling Californians where and how to live.

"Is the public ready to give up mobility in the name of greenhouse gas reductions?" added Contra Costa Transportation Authority director Robert McCleary. He fears lawsuits against major road projects.

Steinberg countered the plan does neither. Instead, he said, it is an obvious next step for California to meet its self-imposed 2020 goals for reducing greenhouse gas emissions, including carbon dioxide from cars, which scientists say play a role in global warming.

Thirty-eight percent of California's greenhouse gas emissions come from cars ferrying residents to work, stores, schools and chores, and from trucks carrying goods to market, state Air Resources Board data show.

The bill instructs metropolitan areas to meld housing and transportation plans into a single document, then to estimate how much greenhouse gas emissions from vehicles that growth will produce.

The Air Resources Board, in turn, will set targets for greenhouse gas emission reductions for each region.

But the bill notably stops short of telling cities and counties which direction to grow. Nor does it require regions to meet ARB greenhouse gas emission targets.

Instead, the bill offers what Steinberg calls a "hard carrot."

Regions that blend land-use and transportation planning in a way that reduces vehicle emissions will be a step ahead in qualifying for state and federal transportation project funds.

Steinberg argues his plan isn't meant to be a death knell for California's suburban lifestyle.

"This is not going to eliminate backyards," he said. "It's more about ensuring that people don't have to spend more time in their cars."

Sacramento's early experience with its 4-year-old Blueprint plan, however, indicates old growth habits are hard to break.

Sprawl in Sacramento has slowed but not stopped. Infill development is happening, but slowly, and transit remains too skeletal to give many residents reason yet to get out of their cars.

To push past those problems, Steinberg says SB 375 offers additional incentives for "smart growth," including relief from certain onerous state environmental review laws for some infill projects and developments near transit stops. Richard Lyon of the state Building Industry Association said those incentives could reduce the number of projects stalled by lawsuits.

The group that put the bill together – dubbed the "coalition of the impossible" by Steinberg – includes builders, environmentalists, cities, housing organizations and transportation planners.

"We're in a new realm," said Sacramento developer Mike Winn, head of the local Building Industry Association chapter. "The (building) model that worked in the past is broken. Even new suburban areas around fringes are going to have to be served by alternative transportation."

Call The Bee's Tony Bizjak, (916) 321-1059.