SACRAMENTO -- Gov. Jerry Brown's proposed budget includes a provision for a $29 million loan from the state to California's bullet train agency, according to a newspaper report.

The little-noticed item in the budget plan would help keep the rail project moving ahead as uncertainty grows about the availability of future funding, the Los Angeles Times reported Wednesday.

The loan to the High-Speed Rail Authority would come from state transportation project accounts. It follows a similar $26 million advance last year from general government revenues, which prompted some lawmakers to complain that such lending would take money from other high-priority projects.

The Los Angeles-to-San Francisco rail project is mired in legal challenges.

At a state Senate hearing last year, rail officials assured lawmakers the state would prevail against lawsuits and be able to repay the loan from $9 billion in voter-approved bonds designated for the project. But a Sacramento judge recently blocked access to that money after finding the rail agency failed to comply with legal restrictions on the bonds.

In addition to the new $29 million loan, the governor is asking for approval to direct $250 million from levies on greenhouse gases generated by businesses to the rail project.

A key project supporter, state Senate President Pro Tem Darrell Steinberg, D-Sacramento, has raised questions about the governor's bullet train financing proposal. Steinberg hasn't indicated whether he will back the latest proposed loan, the Times reported.

The High-Speed Rail Authority declined to comment on the loan and how it would be used.

Rail officials hope to break ground on the first 29-mile segment in the Central Valley this summer.