The Trump administration has launched an investigation into California’s high-speed rail project in what could be the first step in clawing back the $4 billion promised by the Biden administration to build out the first section of the line, from Merced to Bakersfield.

The transportation secretary, Sean Duffy, said the government would conduct a “compliance review” on a $3.1 billion grant, potentially threatening the viability of the troubled project.

While U.S. Transportation Secretary Sean Duffy questioned the cross-state high-speed rail project, he praised the Las Vegas-to-Los Angeles effort.

Duffy, speaking at Union Station in Los Angeles on Thursday morning, said the Federal Railroad Administration will review the rail project and its leadership.

The Trump administration said Thursday it is opening a review into whether to rescind about $4 billion awarded to California's High-Speed Rail project.

President Donald Trump and his administration are performing a compliance review of California's beleaguered high-speed rail that's supposed to link San Francisco with Southern California.