The Brown administration has lowered the projected cost to build California's high-speed rail line by $30 billion -- to $68 billion -- as it braces for crucial hearings in the Legislature, according to sources familiar with the plan.

The lower estimate is tied to a series of changes to the project, primarily by relying on existing rail lines in and around Los Angeles and the Bay Area.

The changes are expected to be announced Monday in Fresno, just five months after the California High-Speed Rail Authority estimated the project could cost $98.5 billion. The business plan underpinning that estimate was widely criticized as inadequate, including by lawmakers and by the rail authority's own peer review group.

Elements of the revised plan were suggested by rail officials weeks ago, including the "blended approach," in which existing tracks in urban areas would be upgraded and eventually used by high-speed rail.

The plan now will rely on a high-speed line down the spine of the state -- from Merced to the San Fernando Valley -- with tie-ins to improved tracks in the Bay Area and Los Angeles.

The approach could result in the authority spending more than $1.5 billion to improve commuter rail service in and around Los Angeles and the Bay Area, pleasing lawmakers in those areas.

The new plan also will abandon the idea of the so-called "train to nowhere," the much criticized initiative to begin the project with a line from near Chowchilla to Corcoran, sources said.

The federal government, which is contributing some $3.3 billion to the project, conditioned funding on starting in the Central Valley.

Now construction is planned to begin in Merced and move south to Lancaster and the San Fernando Valley.

Gov. Jerry Brown is expected to ask the Legislature to appropriate some $2.3 billion in rail bond funds within weeks. This week, he told reporters he spent "several hours" on the project changes.

"We are striving mightily to get a plan that can pass muster and work, and get the train built," Brown said.

The plan still is almost certain to rely, however, on as-yet-unapproved federal funding in future years, a chief complaint of the California High-Speed Rail Peer Review Group.

In a March 21 letter to legislative leaders, the group said it expected the plan "to be changed in significant ways" and would re-evaluate it when it is approved. The rail board is likely to approve the revisions on April 12.

Public opinion turned against the project since voters approved $9 billion in high-speed rail bonds in 2008, and critics roared when the authority in November released its $98.5 billion cost estimate, far higher than its previous estimate of $43 billion.

Brown, a Democrat, embraced that business plan. In the wake of criticism, however, he said the cost would be reduced.

Sen. Joe Simitian, D-Palo Alto, has previously said it would be difficult for the rail authority to produce any plan sufficient to be approved by the Legislature before June, the end of the fiscal year.

When it released its business plan in November, officials said the cost would still fall lower than the cost of airport and highway expansions to accommodate a growing population.

For more stories on high-speed rail, go to fresnobee.com/hsr