The US House of Representatives has narrowly voted to continue collecting data on US phone calls in the first legislative move on the programme.
In a 217-205 vote, lawmakers rejected an effort to restrict the National Security Agency's (NSA) ability to collect electronic information. The NSA's chief had lobbied strongly against the proposed measure.
The vote saw an unusual coalition of conservatives and liberal Democrats against the programme.
Critics say NSA phone data collection is an unwarranted invasion of privacy.
The details of the programme were made public by Edward Snowden, who had worked for America's electronic spying agency.
He is now a fugitive, awaiting a decision on his asylum application in Moscow.