The legal authority for US spy agencies to bulk collect Americans' phone data has expired after the Senate failed to reach a deal, media reported on Monday.
Republican presidential hopeful Rand Paul blocked a Patriot Act extension and it lapsed at midnight on Sunday, BBC reports.
However, the Senate did vote to advance the White House-backed Freedom Act so a new form of data collection is likely to be approved in the coming days.
The Freedom Act imposes more controls, after revelations by Edward Snowden.
The former National Security Agency (NSA) contractor first exposed the extent of the data collection in 2013.
The White House described the expiry of the deadline as an "irresponsible lapse" by the Senate.
"On a matter as critical as our national security, individual senators must put aside their partisan motivations and act swiftly. The American people deserve nothing less," it said in a statement.
The NSA, which runs the majority of surveillance programmes, stopped collecting the affected data at 19.59 on Sunday.
