The ruling in November by a Superior Court judge in Sacramento blocked the state from using $8.6 billion in bond money to finance the first part of the train line, saying officials had failed to explain where they would find the remaining funds. That, in turn, jeopardized California’s access to more than $3 billion in federal matching funds, which are contingent on a state contribution.

In another setback, the state lost a bid to delay an environmental review of the first 29-mile section of the project, raising the prospect of additional costs and delay.

Before the ruling, California had identified nearly $13 billion in financing for the project, which is scheduled for completion in 2029: about $9 billion in state bonds and $3.5 billion in matching funds. Mr. Brown is expected to propose in his state budget on Friday that some funds collected from carbon producers under the state’s cap-and-trade program be used to help pay for the railroad, state officials said. But it remains unclear how much more money is available, and how far it would go to cover the total $68 billion cost of the project.

“I don’t see them getting any more money from the federal government,” Mr. McCarthy said. “I don’t see $9 billion to build it from California taxpayers, and I don’t see them getting any private investment.”