As tensions escalate between California and the Trump administration over immigration, another potential battlefront is emerging over taxes.

The spat began with reports that the Trump administration is considering cutting funding for California’s university system, the largest higher education system in the nation with about 12% of all U.S. enrolled students.

In response, Gov. Gavin Newsom wrote Friday afternoon in a social media post that California provides about $80 billion more in taxes to the federal government than it receives in return.

“Maybe it’s time to cut that off, @realDonaldTrump,” Newsom said.