(TEXAS) -- A federal judge in Texas has ruled the entire Affordable Care Act is unconstitutional.

The ruling came down on Friday (Dec. 14), on the eve of the deadline to sign up for coverage for 2019, CBS News reports.

The ruling now leaves 20 million Americans' health coverage in question.

U.S. District Judge Reed O'Connor gave the decision, citing a recent change in federal tax law that he said makes the act, known as "Obamacare," unconstitutional.

The decision will very likely go to the Supreme Court, CBS News reports.