Zack Whittaker, reporting for ZDNet:An amendment designed to allow the government warrantless access to internet browsing histories has been narrowly defeated in the Senate. The amendment fell two votes short of the required 60 votes to advance. Mitch McConnell (R-KY) switched his vote at the last minute. He submitted a motion to reconsider the vote following the defeat. A new vote may be set for later on Wednesday. Sen. John McCain (R-AZ) introduced the amendment as an add-on to the commerce, justice, and science appropriations bill earlier this week. McCain said in a statement on Monday that the amendment would "track lone wolves" in the wake of the Orlando massacre, in which Omar Mateen, who authorities say radicalized himself online, killed 49 people at a gay nightclub in the Florida city. The amendment, which may be reconsidered in the near future, aims to broaden the rules governing national security letters, which don't require court approval. These letters allow the FBI to demand records associated with Americans' online communications -- so-called electronic communications transactional records.