President Donald Trump has hailed a court decision against Obamacare as "a great ruling for our country,"
But a US government official said the decision by a Texas judge would have no immediate impact on health coverage.
US District Judge Reed O'Connor in Fort Worth, Texas, on Friday said the Obamacare, known formally as the 2010 Affordable Care Act (ACA), was unconstitutional based on its mandate requiring that people buy health insurance.
In a decision that could reach the US Supreme Court, O'Connor sided with a coalition of 20 states that argued that requiring people to pay for insurance coverage was illegal because a change in tax law last year eliminated a penalty for not having health insurance.
"It's a great ruling for our country. We will be able to get great healthcare. We will sit down with the Democrats if the Supreme Court upholds," Trump (right) told reporters.
Trump offered no details on the potential for healthcare talks with the Democrats, who are poised to take majority control of the US House of Representatives in early January. The Senate will remain in Republican hands.
O'Connor's decision was issued the day before the end of a 45-day sign-up period for 2019 health coverage under the law.
The O'Connor ruling underscored the high political stakes involved in the divide over healthcare.