With the California Department of Transportation expected to announce in the coming days that the estimated cost of rebuilding the San Francisco-Oakland Bay Bridge has doubled to $5 billion, a battle is brewing between Southern California and Northern California lawmakers over who should pay.

The latest cost estimate, so politically charged that its release has been delayed several times in recent weeks, is just the latest setback in the 15-year quest to seismically retrofit the landmark Bay Area bridge.

The project began with a cost estimate of $1.1 billion in 1997. But by 2001, the design had changed, and the price tag more than doubled to $2.6 billion. Now, with the bridge half finished and the Department of Transportation refusing to divulge the current cost estimates, legislators say they are hearing the price tag has risen more -- to as much as $5.1 billion.

Some Southern California legislators are demanding that Bay Area residents should cover the added costs through a toll increase on the bridge, which was damaged in the 1989 Loma Prieta earthquake.

Earlier this year, Bay Area residents approved a toll rise from $2 to $3, and now there is talk of raising it to $4 in response to the bridge's rising costs.

"The only alternative is to increase the toll," said state Assemblywoman Jenny Oropeza, a Southern California Democrat and chairwoman of the Assembly's Transportation Committee. "I don't see it as a regional issue, but the reality is, there is no money in the state budget available."

But Bay Area officials balk at this proposal, saying the entire state should share the pain.

"It's outrageous," said state Sen. Liz Figueroa, a Northern California Democrat. "When our economy in Northern California does well, everybody wants to say it fuels the entire state. When it's negative news, it's suddenly a local issue."

"It is always a north-south issue, especially when we're talking about money," Figueroa said. "We need to look at how this affects the entire state."

Southern California transit officials have joined their legislators in calling for higher tolls. They fear their own projects will be jeopardized because of the rising costs of the Bay Bridge.

"The Bay Area spent years trying to decide what the bridge should look like," said Michael Turner, government relations manager for the Metropolitan Transportation Authority in Los Angeles. "We've gone beyond building a bridge. We're now creating a monument."

Turner and other Southern California officials said that while the Bay Bridge project is simply replacing an existing roadway, they have projects competing for the same funds that would widen roads and expand mass transit, doing much more to relieve congestion.

"We have transportation needs down here," he said. "There are a lot of projects here that need to be addressed."

The eastern portion of the Bay Bridge was damaged during the Loma Prieta earthquake. Planners have seen the reconstruction project as a chance to make a bold architectural statement that would place the bridge on par with its more famous neighbor, the Art Deco-towered Golden Gate.

The plans calls for the damaged Oakland side of the span to be replaced by a sleek modern structure built around a 525-foot suspension tower rising from the bay. Artist renderings show the tower illuminated at night and crowned with a beacon.

But the distinctive design has come with a high price tag.

Since 2001, the price for structural steel, on which much of the bridge depends, has risen 50 percent. The tower will require 67,000 tons of steel -- enough to build 10 Eiffel Towers.

As reports of huge cost increases circulate in Sacramento, state Sens. Tom Torlakson and Don Perata from Northern California, have called for an investigation into the Transportation Department's project management.

"There's a lot of people very upset with Caltrans," Torlakson said. "The figures we're hearing are just shocking. . . . I want to know how much of this was external factors like steel and how much of it was just Caltrans misjudgment."

Department officials declined to comment.

The state has few options for covering the extra costs. Among the ideas floated in Sacramento are refinancing bonds, imposing a regional tax on gasoline and raising the bridge toll.

The toll increase may be the easiest way to raise revenue, but the issue is a "political hot potato" with Bay Area commuters, said Mark DeSaulnier, board member of the region's Metropolitan Transportation Commission.

Indeed, Bay Bridge commuters say they are already in sticker shock over the most recent toll increase to $3.

"What they're doing with the tolls just drives me wild," said Deborah Banigan, 54. A sales representative, Banigan commuted across the Bay Bridge for 30 years. But when the tolls continued to rise, she gave up on San Francisco.

"I took another job a few months ago to get out of that racket," she said. "Now, I don't even go near the city, not even for the opera and symphonies. I won't do it. I won't be held hostage for toll money."

Cost estimates for rebuilding the San Francisco-Oakland Bay Bridge are causing a north-south rift in California as the price tag reaches $5 billion.