The Senate has blocked efforts to expand the government's power to investigate suspected terrorists by allowing the FBI to obtain a person's digital fingerprints without first securing a judge's permission.
The 58-38 vote on Wednesday was two short of the 60 necessary to move ahead on the measure. The came 10 days after the massacre at an Orlando nightclub.
It was a victory for civil libertarians and privacy advocates, who complained that the measure would give law enforcement direct access to email and text message logs, internet browsing histories and other online data.
Senior Republican senators who drafted the measure said FBI Director James Comey requested the authority to better arm the agency against foreign terrorist groups.
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