Healthcare subsidies for millions of Americans appear likely to expire after the Senate failed to pass competing bills, a politically fraught issue ahead of next year's midterm elections.
Both Democratic and Republican plans fell short of the 60 votes needed to advance, meaning insurance premiums through the Affordable Care Act (ACA), also known as Obamacare, are on course to more than double at the end of the year.
Opinion polls show a vast majority of Americans favour a subsidy extension, with cost of living a major concern for voters.
The issue has caused a rift among Republicans, with healthcare poised to emerge as a hot issue in next year's congressional elections.
More than 24 million people have health insurance through Obamacare.
