(AP) — The projected cost of California’s bullet train between San Francisco and Los Angeles has jumped to $77 billion and the opening date has been pushed back four years to 2033, according to a business plan released Friday.

The two-year plan presented by the California High-Speed Rail Authority presents the latest setbacks for a project that’s been beleaguered by delays and cost overruns since voters first gave it the greenlight in 2008.

Among the challenges in the latest plan: A lack of money and the difficulty of weaving through mountain passes between Silicon Valley and the inland Central Valley.

“It’s going to be bumpy,” the agency’s new chief executive, Brian Kelly, told The Associated Press in an interview in advance of the plan’s release.

The plan brought fresh fire from critics who doubt the project will ever be completed. The last plan, presented in 2016, estimated the project would cost $64 billion and be open by 2029.

“Let’s cut our losses and use the billions not yet wasted on (high-speed rail) to instead improve freeways, highways and roads and perhaps improve existing rail systems throughout California,” Republican state Sen. Andy Vidak said.

If completed, it would be the nation’s fastest train, carrying people between the two major cities in less than three hours.

Kelly has promised to be more transparent about the project’s challenges, including by assigning costs to every potential risk, such as trouble acquiring land or securing environmental clearance.

While $77 billion is the baseline cost estimate, the plan estimates total costs could be as low as $63.2 billion or as high as $98.1 billion.

The ultimate goal is to connect San Francisco and Los Angeles — and eventually Sacramento and San Diego — but the immediate focus is opening track between San Francisco and the Central Valley, an agriculturally dominant, less-populated portion of inland California.

Rail proponents say linking the two areas would be an economic boon, as housing costs are exploding in the San Francisco Bay Area and the Central Valley is in need of jobs.

That portion of track is now set to be finished by 2029, also marking a four-year delay, and significant challenges remain.

One is how to cross a section of mountains — a critical segment to link Silicon Valley to the Central Valley. Right now, the agency doesn’t have a detailed plan or enough money to do that. The state is looking to build from San Francisco to the west edge of the mountains and from Bakersfield to the east edge of the mountains by 2027 before connecting the two.

How to pay for the entire project remains “uncertain,” Kelly said.

The state has spent $2.5 billion in federal stimulus money and has an additional $930 million in federal money on the table.

That’s on top of a $10 billion bond from voters.

A major source of rail funding is the cap-and-trade program, under which the state auctions permits to release greenhouse gases. Rail planners are currently using the money as it comes in but say they’d need the ability to take on debt that would be paid off with future cap-and-trade dollars.

That would require the Legislature to extend the cap-and-trade program until 2050 and guarantee that money for rail would continue flowing even if auction revenue falls short of expectations. That’s a difficult task for a Legislature that struggled just last year to muster the two-thirds votes needed to extend the program from 2020 to 2030.

There’s a 60-day public-comment period before the rail authority adopts a final plan.