The US government has shut down after Congress failed to pass a key budgetary measure on time.
Lawmakers had hoped to approve a new spending bill before federal funding expired at midnight (05:00 GMT).
But Republican Senator Rand Paul ended hopes for a quick vote when he demanded a debate in the chamber on his amendment to maintain spending caps.
In January, a similar failure to pass a bill led to a three-day government shutdown.
Late on Thursday, as Senator Paul continued to delay the vote, the White House said it was preparing for a possible shutdown.