Critics began panning the first leg of California’s futuristic high-speed rail network as a “train to nowhere” soon after officials decided to build it not in the major population centers of Los Angeles or San Francisco, but through the state’s Central Valley farming belt.

Since then, things have only gotten worse. Spiraling cost estimates and eroding political and public support now threaten a project crucial to a 21st-century vision of train travel that President Obama promised would transform U.S. transportation much as interstate highways did more than a half-century ago.

A national high-speed rail network would not only support tens of thousands of construction and manufacturing jobs, but it would get Americans out of their cars, revitalize struggling downtowns, and spare the environment millions of tons of carbon emissions and travelers untold hours wasted in traffic or in airport terminals waiting out delays.

Obama set a goal of providing 80 percent of Americans access to high-speed rail within 25 years. But that lofty vision is yielding to the political gravity generated by high costs, determined opponents and a public that has grown dubious of government’s ability to do big things.

Virtually none of the projects has gotten off the ground, and the one that has is in trouble.

For Obama, the political stakes are high going into the 2012 election. Republican front-runner Mitt Romney has accused him of putting too much faith in government to build the economy. The president, Romney says to the delight of Republican partisans, “does not know” how business, or the economy, works.

The plan that envisions bullet trains trains zipping between the nation’s major cities at speeds up to 220 miles per hour, was one of the few transformative projects included in the $797 billion stimulus program enacted early in Obama’s presidency.

“Imagine whisking through towns at speeds over 100 miles an hour, walking only a few steps to public transportation, and ending up just blocks from your destination,” Obama said in announcing his vision for high-speed rail in April 2009. “Imagine what a great project that would be to rebuild America.”

So far, Obama has wagered more than $10 billion in federal money on high-speed rail, only to see his plans diminished, one after another.

Republican governors in Florida, Wisconsin and Ohio turned back billions of dollars in federal money for high-speed rail, denouncing the proposals as both the creation of Big Government and as economically unfeasible.

The objections in those three states left money to be redirected to a host of projects that promise to relieve bottlenecks and speed up traditional rail service in many parts of the country. In one case, the 285-mile trip between Chicago and Detroit will be reduced 30 minutes from the current 51 / 2 hours. But those improvements fall short of the transformative promise of high-speed rail.

House Republicans were also among those who dug in against Obama’s high-speed rail vision, saying that outside of select regions, it did not fit a sprawling, car-loving nation served by nearly 50,000 miles of interstate highways and an extensive air travel network.

Now the nation’s only pending true high-speed rail project is facing a crisis moment in California, a Democratic stronghold known for its innovation.

Few places would benefit more from the trains. California’s urban areas are notorious for hair-raising traffic jams. The skies between San Francisco and Los Angeles — the country’s busiest route — are so packed that 25 percent of the flights between the two cities are at least one hour late, according to state officials. And with the state’s population projected to soar by 50 percent over the next four decades, the congestion is expected only to grow more dire.

Meanwhile, California’s fast-growing Central Valley, where cities such as Fresno, Merced and Bakersfield struggle with unemployment rates in the mid-teens, would benefit economically from a swift, reliable and relatively low-cost connection to the state’s major business hubs, not to mention the jobs the project would create.

“California is going to be one of the nation’s fastest growing states, and one of the reasons people want high-speed rail is to get out of the congestion,” Transportation Secretary Ray LaHood said. “California needs a mix of transportation. The state does not have enough highways to accommodate the growth that is going to happen.”

More than a decade ago, the state formed a High-Speed Rail Authority to begin planning the system. In 2008, despite crushing state budget problems, California voters approved a referendum to sell nearly $10 billion in bonds to begin funding the project, which would cut the travel time between downtown Los Angeles and downtown San Francisco to less than 3 hours.

When the Obama administration kicked in nearly $3.5 billion in stimulus money, the project seemed to be on track to break ground later this year.

But since then, things have gone awry. Rather than beginning in one of the state’s congested major cities, planners decided to build the first phase of the project along a 130-mile stretch of the Central Valley.

The idea was that land would be cheapest and construction easiest there, allowing the state to meet deadlines for spending the federal stimulus money and to build more miles of track for the dollar. In addition, the miles of relatively straight track would be an excellent proving ground for the high-speed rail technology.

Still, many were baffled by the idea of sinking $6 billion into a rail line that runs from just south of Merced to just north of Bakersfield.

“The right place to start our investment in passenger rail in California is the LA basin, the most densely populated area of the state and home to crippling congestion,” said Bill Shuster (R-Pa.), chairman of a railroads subcommittee in the House.

Elizabeth Goldstein Alexis, co-founder of a watchdog group called Californians Advocating Responsible Rail Design, said that the Central Valley tracks would bypass many of the cities along the route, while, among other problems, causing the train station in Fresno to move away from major government buildings. In addition, said Alexis, an economist, the planning scenarios for the project contain fundamental errors.

“The entire planning process has been chaotic,” said Alexis, who says she voted for the rail bond measure. “We need to build a good process around this.”

Beyond that, the estimated cost of the rail network has tripled from earlier estimates, to nearly $100 billion. Planners are at a loss to say where they will get the bulk of the money needed to complete it. And the completion date for the 800-mile system has been pushed back from 2020 to 2033.

Meanwhile, a recent poll indicated that public sentiment in California has turned against the project.

Earlier this month, a key government review committee said the state should not release bonds to start building the railroad until the project is rethought — a decision that has helped throw the entire enterprise into limbo.

In a letter released earlier this month, California Sen. Dianne Feinstein (D), a supporter of high-speed rail, has called on Gov. Jerry Brown (D) to move “swiftly to address the high-speed rail project’s problems.”

She echoed six major areas cited by the peer review group that need to be rethought, including the need to invest initial funding into the state’s congested urban corridors.

Still, Brown seems committed to pushing ahead even as he makes adjustments on the fly. Earlier this month, he moved planning for high-speed rail into the state’s transportation agency, a decision aimed at better integrating transportation planning.

But others are urging the governor to slow down, even if it means busting a 2017 deadline for spending all of the stimulus money earmarked for the project.

“I feel like right now we are faced with two bad choices,” said state Sen. Joe Simitian, (D), who chairs a key subcommittee overseeing high-speed rail spending. “One bad choice is to kill the whole project. But the other is to say let’s spend $6.2 billion because we are being rushed into it because we could lose federal funding. What we have to do is take a deep breath, take a step back and re-evaluate the entire project. We don’t want to end up making a $100 billion mistake.”