California Gov. Gavin Newsom threatened to block federal tax payments from his state on Friday, escalating tensions with President Donald Trump amid reports that the White House may cut federal funding to California, Breitbart reported.

"Californians pay the bills for the federal government. We pay over $80 BILLION more in taxes than we get back. Maybe it's time to cut that off, @realDonaldTrump," Newsom posted on X Friday.

The constitutional authority of Newsom to withhold federal taxes on behalf of individuals, businesses, and other entities within the state appears not to be clearly defined.

Breitbart News reported that the Trump White House might cut federal funding to California due to its opposition to the Trump administration's policies.

Despite a significant budget deficit and requests for federal aid — including $40 billion for fire relief — Newsom continues to challenge Trump administration policies through lawsuits, aiming for nationwide injunctions.

The administration's potential move to withhold funding comes from broader tensions between the federal government and the state of California. The Trump administration has expressed frustration over California's frequent legal challenges and policy defiance.

Trump threatened to cut California's sports funding due to its opposition to a federal transgender policy.

This week, the U.S. Department of Transportation suggested reclaiming billions spent on California's high-speed rail project.

California Democrats believe they can oppose federal policies yet still receive federal funds due to the state's significant contributions to federal revenue. They also dismiss linking disaster aid, like wildfire relief, to political compliance.

A tax revolt led by the state could revive memories of the "nullification" doctrine advanced by some Southern states before the Civil War. Analysts have pointed out that such a move could backfire by triggering a tax revolt against the state's sky-high taxes on Californians.