An explosive court ruling to wipe out Obamacare has revived the acrimonious health care battle in Washington and tossed a political bomb in President Donald Trump's lap as he gears up to run for re-election.

The case may not be resolved in the courts before 2020, legal experts said, which could make it a defining issue in the race for the White House and Congress.

Democrats immediately jumped on the Friday night ruling to warn that health care coverage for millions of Americans was at stake due to the Republican-led lawsuit that sought to void popular parts of Obamacare, including protections for pre-existing conditions and a ban on annual lifetime limits.