The California High-Speed Rail Authority has dropped its lawsuit against the Trump administration over the termination of $4 billion in federal grants for the state's high-speed rail project, opting instead to pursue private investment.

Attorney General Rob Bonta of California filed a notice of dismissal on Tuesday, ending the federal lawsuit that the state had brought in July in the Eastern District of California.

The defendants in the case were the Transportation Department and the Federal Railroad Administration, which had decided in June to cut the funding.

The Transportation Department said a compliance review found that California had failed to meet federal grant requirements, citing costly changes to contracts, lowered ridership forecasts and missed deadlines.

The project has long been a source of frustration in California, plagued by delays, rising costs and scaled-back ambitions since voters first approved it in 2008.

The funding termination came amid increasingly fraught relations between the Trump administration and Democratic leaders in California, the nation’s largest state. The two grant tranches totaling $4 billion had been approved under the Obama and Biden administrations.

The authority said in a statement on Saturday that its decision to drop the lawsuit “reflects the state’s assessment that the federal government is not a reliable, constructive or trustworthy partner in advancing high-speed rail in California.”

The statement continued: “The Federal Railroad Administration stated that all work performed by the authority — whether undertaken as part of cooperative agreements or otherwise — remains ‘at risk’ and may not receive funding. Combined with the administration’s persistent lack of good-faith engagement, this made clear that the federal government is unlikely to uphold its commitments to California. As a result, the state has opted to move forward without the Trump administration.”

In a statement on Tuesday, the High-Speed Rail Authority said it had begun seeking private investors and developers to join the project by next summer. About 80 miles of guideway have been completed in the Central Valley, according to the authority.

California officials have said that limited passenger service would begin in the Central Valley by 2033. The original plan envisioned 500 miles of rail track between Los Angeles and San Francisco by 2020, eventually extending north to Sacramento and south to San Diego.