SACRAMENTO, Calif. (AP) — California lawmakers gave the green light to start building the nation's first dedicated high-speed rail line, a multibillion dollar project that will eventually link Los Angeles and San Francisco.

The move marked major political victories for Democratic Gov. Jerry Brown and the Obama administration. Both have promoted bullet trains as job generators and clean transportation alternatives.

In a narrow 21-16 party-line vote that involved intense lobbying by the governor, legislative leaders and labor groups, the state Senate approved the measure marking the launch of California's ambitious bullet train, which has spent years in the planning stages.

"The Legislature took bold action today that gets Californians back to work and puts California out in front once again," Brown said.

Brown pushed for the massive infrastructure project to accommodate expected growth in the nation's most populous state, which now has 37 million people. State and federal officials also said high-speed rail would create jobs.

"No economy can grow faster than its transportation network allows," U.S. Transportation Secretary Ray LaHood said in a statement. "With highways between California cities congested and airspace at a premium, Californians desperately need an alternative."

The bill authorizes the state to begin selling $4.5 billion in voter-approved bonds that includes $2.6 billion to build an initial 130-mile stretch of the high-speed rail line in the agriculturally rich Central Valley. That allows the state to draw another $3.2 billion in federal funding.

The first segment of the line will run from Madera to Bakersfield.

Senate Republicans blasted the decision, citing the state's ongoing budget problems. They said project would push California over a fiscal cliff. No GOP senators voted for the bill Friday.

The final cost of the completed project from Los Angeles to San Francisco is projected to be $68 billion.

"It's unfortunate that the majority would rather spend billions of dollars that we don't have for a train to nowhere than keep schools open and harmless from budget cuts," Sen. Tom Harman, R-Huntington Beach, said in a statement.

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Dan Richard, chairman of the California High-Speed Rail Authority, which is managing the project, said California would have lost billions of dollars in federal aid if the Senate fails to pass the bill before adjourning Friday for a monthlong recess.

California entered a contract that called for the federal government to provide money for building the Central Valley segment if the state also put up its share, he said.

"Not only will California be the first state in the nation to build a high-speed rail system to connect our urban centers, we will also modernize and improve rail systems at the local and regional level," Richard said Friday.

California was able to secure more federal aid than expected after Florida, Ohio and Wisconsin turned down money.

Before Friday's vote, at least half a dozen Democrats in the 40-member Senate remained opposed, skeptical or uncommitted. Some were concerned about how the vote would impact their political futures, while others were wary about financing and management of the massive project.

In recent days, Democratic leaders included more state funding to improve existing rail systems in an effort to entice support for the bullet train.

The bill authorizes the state to sell nearly half of a $10 billion high-speed rail bond that voters approved four years ago under Proposition 1A. In addition to financing the first segment of high-speed rail, it allocates a total of $1.9 billion in bonds for regional rail improvements in Northern and Southern California.

The upgrades include electrifying Caltrain, a San Jose-San Francisco commuter line, and improving Metrolink commuter lines in Southern California.

One dissenter, Sen. Joe Simitian, D-Palo Alto, said public support had waned for the project, and there were too many questions about financing to complete it.

"Is there additional commitment of federal funds? There is not. Is there additional commitment of private funding? There is not. Is there a dedicated funding source that we can look to in the coming years? There is not," Simitian said.

The Bay Area Council, a group of business leaders from the San Francisco Bay and Silicon Valley areas, cheered the vote.

The bill, which already passed the state Assembly, heads to Brown for his signature.