Fallout from a Guardian story that exposed how anonymous messaging app Whisper tracked users continued Thursday as Senate Commerce Committee Chairman Jay Rockefeller, a West Virginia Democrat who is retiring this year, demanded a briefing from the startup about its data retention and user tracking practices. “It is questionable, at best, whether users seeking to post anonymously on the ‘safest place on the Internet,’ would expect that WhisperText has information sharing relationships with third parties such as media organizations,” Rockefeller wrote.

Whisper’s CEO, Michael Heyward, issued this statement: “We share the Senator’s interest in protecting consumer privacy and will respond shortly. Though we disagree with the Guardian’s reporting, we welcome the discussion.”