Key parts of the post-September 11 Patriot Act that allow U.S. spy agencies to bulk collect phone data has expired after the U.S. Senate failed to reach a deal by a midnight deadline.
A vote on the Freedom Act, a revised bill that provides for greater control on phone-data collection, will not take place until later in the week.
The bill, which passed the House of Representatives this month, overcame an early procedural hurdle May 31 when the Senate met for an emergency session.
But it failed to move ahead further once Senator Rand Paul, a Republican 2016 presidential candidate opposed to the bulk-data collection and the bill that reforms the program, signaled he would block attempts to advance it.
The White House said it was 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 failure to reach a deal means that the National Security Agency (NSA) will temporarily lose the right to bulk collect phone records, to monitor terrorism suspects, and to carry out "roving wiretaps" of suspects.
Earlier on May 31, the NSA began switching off its servers that collect metadata.